diff --git a/.github/subtrees.json b/.github/subtrees.json
new file mode 100644
index 00000000..2e7193a9
--- /dev/null
+++ b/.github/subtrees.json
@@ -0,0 +1,37 @@
+[
+  {
+    "prefix": "src",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/iphreeqc-src.git",
+    "repo": "usgs-coupled-subtrees/iphreeqc-src"
+  },
+  {
+    "prefix": "examples/c",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc-commanuscript-cgfinal-examples-c.git",
+    "repo": "usgs-coupled-subtrees/phreeqc-commanuscript-cgfinal-examples-c"
+  },
+  {
+    "prefix": "examples/com",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc-commanuscript-cgfinal-examples-com.git",
+    "repo": "usgs-coupled-subtrees/phreeqc-commanuscript-cgfinal-examples-com"
+  },
+  {
+    "prefix": "examples/fortran",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc-COMManuscript-CGfinal-examples-fortran.git",
+    "repo": "usgs-coupled-subtrees/phreeqc-COMManuscript-CGfinal-examples-fortran"
+  },
+  {
+    "prefix": "database",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc3-database.git",
+    "repo": "usgs-coupled-subtrees/phreeqc3-database"
+  },
+  {
+    "prefix": "phreeqc3-doc",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc3-doc.git",
+    "repo": "usgs-coupled-subtrees/phreeqc3-doc"
+  },
+  {
+    "prefix": "phreeqc3-examples",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc3-examples.git",
+    "repo": "usgs-coupled-subtrees/phreeqc3-examples"
+  }
+]
\ No newline at end of file
diff --git a/.github/workflows/lint-subtrees.yml b/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/.github/workflows/subtree.yml b/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/database/.github/subtrees.json b/database/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/database/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/database/.github/superprojects.json b/database/.github/superprojects.json
new file mode 100644
index 00000000..c1048e5a
--- /dev/null
+++ b/database/.github/superprojects.json
@@ -0,0 +1,11 @@
+{
+  "usgs-coupled-subtrees/phreeqc3-database": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phreeqcrm",
+      "usgs-coupled-subtrees/phreeqc3",
+      "usgs-coupled-subtrees/wphast"
+    ]
+  }
+}
diff --git a/database/.github/workflows/lint-subtrees.yml b/database/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/database/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/database/.github/workflows/lint-superprojects.yml b/database/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..c157704f
--- /dev/null
+++ b/database/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,20 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
+          # skip-repos: |
+          #   - usgs-coupled-subtrees/iphreeqccom
+          #   - usgs-coupled-subtrees/phreeqcrm-src
+
diff --git a/database/.github/workflows/subtree.yml b/database/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/database/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/c/.github/subtrees.json b/examples/c/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/examples/c/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/examples/c/.github/superprojects.json b/examples/c/.github/superprojects.json
new file mode 100644
index 00000000..c04bbc0d
--- /dev/null
+++ b/examples/c/.github/superprojects.json
@@ -0,0 +1,9 @@
+{
+  "usgs-coupled-subtrees/phreeqc-commanuscript-cgfinal-examples-c": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phreeqc"
+    ]
+  }
+}
diff --git a/examples/c/.github/workflows/lint-subtrees.yml b/examples/c/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/examples/c/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/c/.github/workflows/lint-superprojects.yml b/examples/c/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/examples/c/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/c/.github/workflows/subtree.yml b/examples/c/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/examples/c/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/com/.github/subtrees.json b/examples/com/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/examples/com/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/examples/com/.github/superprojects.json b/examples/com/.github/superprojects.json
new file mode 100644
index 00000000..b865fe72
--- /dev/null
+++ b/examples/com/.github/superprojects.json
@@ -0,0 +1,9 @@
+{
+  "usgs-coupled-subtrees/phreeqc-commanuscript-cgfinal-examples-com": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phreeqc"
+    ]
+  }
+}
diff --git a/examples/com/.github/workflows/lint-subtrees.yml b/examples/com/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/examples/com/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/com/.github/workflows/lint-superprojects.yml b/examples/com/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/examples/com/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/com/.github/workflows/subtree.yml b/examples/com/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/examples/com/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/fortran/.github/subtrees.json b/examples/fortran/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/examples/fortran/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/examples/fortran/.github/superprojects.json b/examples/fortran/.github/superprojects.json
new file mode 100644
index 00000000..951d3f2d
--- /dev/null
+++ b/examples/fortran/.github/superprojects.json
@@ -0,0 +1,9 @@
+{
+  "usgs-coupled-subtrees/phreeqc-COMManuscript-CGfinal-examples-fortran": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phreeqc"
+    ]
+  }
+}
diff --git a/examples/fortran/.github/workflows/lint-subtrees.yml b/examples/fortran/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/examples/fortran/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/fortran/.github/workflows/lint-superprojects.yml b/examples/fortran/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/examples/fortran/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/examples/fortran/.github/workflows/subtree.yml b/examples/fortran/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/examples/fortran/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/phreeqc3-doc/.github/subtrees.json b/phreeqc3-doc/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/phreeqc3-doc/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/phreeqc3-doc/.github/superprojects.json b/phreeqc3-doc/.github/superprojects.json
new file mode 100644
index 00000000..837f958a
--- /dev/null
+++ b/phreeqc3-doc/.github/superprojects.json
@@ -0,0 +1,10 @@
+{
+  "usgs-coupled-subtrees/phreeqc3-doc": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phast3-doc",
+      "usgs-coupled-subtrees/phreeqc3"
+    ]
+  }
+}
diff --git a/phreeqc3-doc/.github/workflows/lint-subtrees.yml b/phreeqc3-doc/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/phreeqc3-doc/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/phreeqc3-doc/.github/workflows/lint-superprojects.yml b/phreeqc3-doc/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/phreeqc3-doc/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/phreeqc3-doc/.github/workflows/subtree.yml b/phreeqc3-doc/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/phreeqc3-doc/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/phreeqc3-examples/.github/subtrees.json b/phreeqc3-examples/.github/subtrees.json
new file mode 100644
index 00000000..fe51488c
--- /dev/null
+++ b/phreeqc3-examples/.github/subtrees.json
@@ -0,0 +1 @@
+[]
diff --git a/phreeqc3-examples/.github/workflows/lint-subtrees.yml b/phreeqc3-examples/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..71d8e58f
--- /dev/null
+++ b/phreeqc3-examples/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,19 @@
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/phreeqc3-examples/.github/workflows/subtree.yml b/phreeqc3-examples/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/phreeqc3-examples/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/.github/subtrees.json b/src/.github/subtrees.json
new file mode 100644
index 00000000..352be8c8
--- /dev/null
+++ b/src/.github/subtrees.json
@@ -0,0 +1,7 @@
+[
+  {
+    "prefix": "phreeqcpp",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc3-src.git",
+    "repo": "usgs-coupled-subtrees/phreeqc3-src"
+  }
+]
\ No newline at end of file
diff --git a/src/.github/superprojects.json b/src/.github/superprojects.json
new file mode 100644
index 00000000..bbc77cf2
--- /dev/null
+++ b/src/.github/superprojects.json
@@ -0,0 +1,9 @@
+{
+  "usgs-coupled-subtrees/iphreeqc-src": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc",
+      "usgs-coupled-subtrees/iphreeqccom",
+      "usgs-coupled-subtrees/phreeqcrm-src"
+    ]
+  }
+}
diff --git a/src/.github/workflows/lint-subtrees.yml b/src/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..7af56b67
--- /dev/null
+++ b/src/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,22 @@
+# This workflow lints the subtrees.json file to ensure it is valid and up-to-date.
+# It is triggered on pull requests that modify the subtrees.json file or can be run manually
+# via the GitHub Actions UI.
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/.github/workflows/lint-superprojects.yml b/src/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/src/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/.github/workflows/subtree.yml b/src/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/src/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/phreeqcpp/.github/subtrees.json b/src/phreeqcpp/.github/subtrees.json
new file mode 100644
index 00000000..ff31b0dd
--- /dev/null
+++ b/src/phreeqcpp/.github/subtrees.json
@@ -0,0 +1,7 @@
+[
+  {
+    "prefix": "common",
+    "url": "git@${CI_SERVER_HOST}:${GROUP}-subtrees/phreeqc3-src-common.git",
+    "repo": "usgs-coupled-subtrees/phreeqc3-src-common"
+  }
+]
\ No newline at end of file
diff --git a/src/phreeqcpp/.github/superprojects.json b/src/phreeqcpp/.github/superprojects.json
new file mode 100644
index 00000000..97e0591c
--- /dev/null
+++ b/src/phreeqcpp/.github/superprojects.json
@@ -0,0 +1,8 @@
+{
+  "usgs-coupled-subtrees/phreeqc3-src": {
+    "superprojects": [
+      "usgs-coupled-subtrees/iphreeqc-src",
+      "usgs-coupled-subtrees/phreeqc3"
+    ]
+  }
+}
diff --git a/src/phreeqcpp/.github/workflows/lint-subtrees.yml b/src/phreeqcpp/.github/workflows/lint-subtrees.yml
new file mode 100644
index 00000000..7af56b67
--- /dev/null
+++ b/src/phreeqcpp/.github/workflows/lint-subtrees.yml
@@ -0,0 +1,22 @@
+# This workflow lints the subtrees.json file to ensure it is valid and up-to-date.
+# It is triggered on pull requests that modify the subtrees.json file or can be run manually
+# via the GitHub Actions UI.
+name: Lint subtrees.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/subtrees.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-subtrees:
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-subtrees/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/phreeqcpp/.github/workflows/subtree.yml b/src/phreeqcpp/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/src/phreeqcpp/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/phreeqcpp/common/.github/superprojects.json b/src/phreeqcpp/common/.github/superprojects.json
new file mode 100644
index 00000000..89a9ab74
--- /dev/null
+++ b/src/phreeqcpp/common/.github/superprojects.json
@@ -0,0 +1,7 @@
+{
+  "usgs-coupled-subtrees/phreeqc3-src-common": {
+    "superprojects": [
+      "usgs-coupled-subtrees/phreeqc3-src"
+    ]
+  }
+}
diff --git a/src/phreeqcpp/common/.github/workflows/lint-superprojects.yml b/src/phreeqcpp/common/.github/workflows/lint-superprojects.yml
new file mode 100644
index 00000000..b46ff4bc
--- /dev/null
+++ b/src/phreeqcpp/common/.github/workflows/lint-superprojects.yml
@@ -0,0 +1,16 @@
+name: Lint superprojects.json
+
+on:
+  pull_request:
+    paths:
+      - '.github/superprojects.json'
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  lint-superprojects:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: usgs-coupled-subtrees/sync-subtrees-action/lint-superprojects/@main
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
diff --git a/src/phreeqcpp/common/.github/workflows/subtree.yml b/src/phreeqcpp/common/.github/workflows/subtree.yml
new file mode 100644
index 00000000..b4527205
--- /dev/null
+++ b/src/phreeqcpp/common/.github/workflows/subtree.yml
@@ -0,0 +1,37 @@
+name: Sync Subtrees
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'If true, don’t push any changes (for testing only).'
+        required: true
+        default: false
+        type: boolean
+      testMerge:
+        description: 'Run in test mode, pushing to a test branch.'
+        required: true
+        default: false
+        type: boolean
+
+jobs:
+  sync-subtrees:
+    if: startsWith(github.repository, 'usgs-coupled-subtrees/')
+    runs-on: ubuntu-latest
+    env:
+      CI_SERVER_HOST: github.com
+      GROUP: usgs-coupled
+      GH_TOKEN: ${{ secrets.WORKFLOW_PAT }}
+    steps:
+      - name: Run sync-subtrees-action
+        uses: usgs-coupled-subtrees/sync-subtrees-action@main
+        with:
+          dryRun: ${{ inputs.dryRun }}
+          testMerge: ${{ inputs.testMerge }}
+          repository_name: ${{ github.event.repository.name }}
+          default_branch: ${{ github.event.repository.default_branch }}
+          run_number: ${{ github.run_number }}
+          ssh_private_key: ${{ secrets.SSH_PRIVATE_KEY }}