diff --git a/.github/workflows/upgrade_downgrade_test_onlineddl_old.yml b/.github/workflows/upgrade_downgrade_test_onlineddl_old.yml
new file mode 100644
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+++ b/.github/workflows/upgrade_downgrade_test_onlineddl_old.yml
@@ -0,0 +1,187 @@
+name: Online DDL old parent with new replicas - Upgrade Downgrade Testing
+on:
+  push:
+  pull_request:
+
+concurrency:
+  group: format('{0}-{1}', ${{ github.ref }}, 'Upgrade Downgrade Testing Reparent Old VTTablet')
+  cancel-in-progress: true
+
+permissions: read-all
+
+# This test ensures that our end-to-end tests work using Vitess components
+# (vtctl, vttablet, etc) built on different versions.
+
+jobs:
+
+  upgrade_downgrade_test:
+    name: Run Upgrade Downgrade Test - Reparent Old VTTablet
+    runs-on: gh-hosted-runners-16cores-1
+
+    steps:
+    - name: Skip CI
+      run: |
+        if [[ "${{contains( github.event.pull_request.labels.*.name, 'Skip CI')}}" == "true" ]]; then
+          echo "skipping CI due to the 'Skip CI' label"
+          exit 1
+        fi
+
+    - name: Check if workflow needs to be skipped
+      id: skip-workflow
+      run: |
+        skip='false'
+        if [[ "${{github.event.pull_request}}" ==  "" ]] && [[ "${{github.ref}}" != "refs/heads/main" ]] && [[ ! "${{github.ref}}" =~ ^refs/heads/release-[0-9]+\.[0-9]$ ]] && [[ ! "${{github.ref}}" =~ "refs/tags/.*" ]]; then
+          skip='true'
+        fi
+        echo Skip ${skip}
+        echo "skip-workflow=${skip}" >> $GITHUB_OUTPUT
+
+    - name: Check out commit's code
+      if: steps.skip-workflow.outputs.skip-workflow == 'false'
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Set output with latest release branch
+      id: output-previous-release-ref
+      if: steps.skip-workflow.outputs.skip-workflow == 'false'
+      run: |
+        previous_release_ref=$(./tools/get_previous_release.sh ${{github.base_ref}} ${{github.ref}})
+        echo $previous_release_ref
+        echo "previous_release_ref=${previous_release_ref}" >> $GITHUB_OUTPUT
+
+    - name: Check for changes in relevant files
+      if: steps.skip-workflow.outputs.skip-workflow == 'false'
+      uses: dorny/paths-filter@v3.0.1
+      id: changes
+      with:
+        token: ''
+        filters: |
+          end_to_end:
+            - 'go/**'
+            - 'go/**/*.go'
+            - 'test.go'
+            - 'Makefile'
+            - 'build.env'
+            - 'go.sum'
+            - 'go.mod'
+            - 'proto/*.proto'
+            - 'tools/**'
+            - 'config/**'
+            - 'bootstrap.sh'
+            - '.github/workflows/upgrade_downgrade_test_reparent_old_vttablet.yml'
+
+    - name: Set up Go
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      uses: actions/setup-go@v5
+      with:
+        go-version: 1.22.3
+
+    - name: Set up python
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      uses: actions/setup-python@v5
+
+    - name: Tune the OS
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        sudo sysctl -w net.ipv4.ip_local_port_range="22768 65535"
+
+    - name: Get base dependencies
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        sudo DEBIAN_FRONTEND="noninteractive" apt-get update
+        # Uninstall any previously installed MySQL first
+        sudo systemctl stop apparmor
+        sudo DEBIAN_FRONTEND="noninteractive" apt-get remove -y --purge mysql-server mysql-client mysql-common
+        sudo apt-get -y autoremove
+        sudo apt-get -y autoclean
+        sudo deluser mysql
+        sudo rm -rf /var/lib/mysql
+        sudo rm -rf /etc/mysql
+        # Install mysql80
+        sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys A8D3785C
+        wget -c https://dev.mysql.com/get/mysql-apt-config_0.8.29-1_all.deb
+        echo mysql-apt-config mysql-apt-config/select-server select mysql-8.0 | sudo debconf-set-selections
+        sudo DEBIAN_FRONTEND="noninteractive" dpkg -i mysql-apt-config*
+        sudo apt-get update
+        sudo DEBIAN_FRONTEND="noninteractive" apt-get install -y mysql-server mysql-client
+        # Install everything else we need, and configure
+        sudo apt-get install -y make unzip g++ etcd curl git wget eatmydata
+        sudo service mysql stop
+        sudo service etcd stop
+        sudo bash -c "echo '/usr/sbin/mysqld { }' > /etc/apparmor.d/usr.sbin.mysqld" # https://bugs.launchpad.net/ubuntu/+source/mariadb-10.1/+bug/1806263
+        sudo ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/
+        sudo apparmor_parser -R /etc/apparmor.d/usr.sbin.mysqld || echo "could not remove mysqld profile"
+
+        # install JUnit report formatter
+        go install github.com/vitessio/go-junit-report@HEAD
+
+        wget https://repo.percona.com/apt/percona-release_latest.$(lsb_release -sc)_all.deb
+        sudo apt-get install -y gnupg2
+        sudo dpkg -i percona-release_latest.$(lsb_release -sc)_all.deb
+        sudo apt-get update
+        sudo apt-get install -y percona-xtrabackup-24
+
+    # Checkout to the last release of Vitess
+    - name: Check out other version's code (${{ steps.output-previous-release-ref.outputs.previous_release_ref }})
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      uses: actions/checkout@v4
+      with:
+        ref: ${{ steps.output-previous-release-ref.outputs.previous_release_ref }}
+
+    - name: Get dependencies for the last release
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        go mod download
+
+    - name: Building last release's binaries
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      timeout-minutes: 10
+      run: |
+        source build.env
+        NOVTADMINBUILD=1 make build
+        mkdir -p /tmp/vitess-build-other/
+        cp -R bin /tmp/vitess-build-other/
+        rm -Rf bin/*
+
+    # Checkout to this build's commit
+    - name: Check out commit's code
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      uses: actions/checkout@v4
+
+    - name: Get dependencies for this commit
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        go mod download
+
+    - name: Building the binaries for this commit
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      timeout-minutes: 10
+      run: |
+        source build.env
+        NOVTADMINBUILD=1 make build
+        mkdir -p /tmp/vitess-build-current/
+        cp -R bin /tmp/vitess-build-current/
+
+    # Swap the binaries. Use vtctl version n and keep vttablet at version n-1
+    - name: Use current version Vtctl, and other version VTTablet
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        source build.env
+
+        rm -f $PWD/bin/vttablet $PWD/bin/mysqlctl $PWD/bin/mysqlctld
+        cp /tmp/vitess-build-other/bin/vttablet $PWD/bin/vttablet
+        cp /tmp/vitess-build-other/bin/mysqlctl $PWD/bin/mysqlctl
+        cp /tmp/vitess-build-other/bin/mysqlctld $PWD/bin/mysqlctld
+        vtctl --version
+        vttablet --version
+
+    # Running a test with vtctl at version n and vttablet at version n-1
+    - name: Run reparent tests (vtctl=N, vttablet=N-1)
+      if: steps.skip-workflow.outputs.skip-workflow == 'false' && steps.changes.outputs.end_to_end == 'true'
+      run: |
+        rm -rf /tmp/vtdataroot
+        mkdir -p /tmp/vtdataroot
+
+        source build.env
+        eatmydata -- go run test.go -skip-build -keep-data=false -docker=false -print-log -follow -tag upgrade_downgrade_reparent