diff --git a/stack_orchestrator/deploy/deployment_create.py b/stack_orchestrator/deploy/deployment_create.py
index 5daffad8..59188b95 100644
--- a/stack_orchestrator/deploy/deployment_create.py
+++ b/stack_orchestrator/deploy/deployment_create.py
@@ -443,16 +443,17 @@ def _check_volume_definitions(spec):
 @click.command()
 @click.option("--spec-file", required=True, help="Spec file to use to create this deployment")
 @click.option("--deployment-dir", help="Create deployment files in this directory")
+@click.option("--sync", is_flag=True, default=False, help="Update existing deployment directory without overwriting data volumes")
 @click.argument('extra_args', nargs=-1, type=click.UNPROCESSED)
 @click.pass_context
-def create(ctx, spec_file, deployment_dir, extra_args):
+def create(ctx, spec_file, deployment_dir, sync, extra_args):
     deployment_command_context = ctx.obj
-    return create_operation(deployment_command_context, spec_file, deployment_dir, extra_args)
+    return create_operation(deployment_command_context, spec_file, deployment_dir, sync, extra_args)
 
 
 # The init command's implementation is in a separate function so that we can
 # call it from other commands, bypassing the click decoration stuff
-def create_operation(deployment_command_context, spec_file, deployment_dir, extra_args):
+def create_operation(deployment_command_context, spec_file, deployment_dir, sync, extra_args):
     parsed_spec = Spec(os.path.abspath(spec_file), get_parsed_deployment_spec(spec_file))
     _check_volume_definitions(parsed_spec)
     stack_name = parsed_spec["stack"]
@@ -466,12 +467,21 @@ def create_operation(deployment_command_context, spec_file, deployment_dir, extr
     else:
         deployment_dir_path = Path(deployment_dir)
     if deployment_dir_path.exists():
-        error_exit(f"{deployment_dir_path} already exists")
-    os.mkdir(deployment_dir_path)
+        if not sync:
+            error_exit(f"{deployment_dir_path} already exists")
+        if opts.o.debug:
+            print(f"Syncing existing deployment at {deployment_dir_path}")
+    else:
+        if sync:
+            error_exit(f"--sync requires that {deployment_dir_path} already exists")
+        os.mkdir(deployment_dir_path)
     # Copy spec file and the stack file into the deployment dir
     copyfile(spec_file, deployment_dir_path.joinpath(constants.spec_file_name))
     copyfile(stack_file, deployment_dir_path.joinpath(constants.stack_file_name))
-    _create_deployment_file(deployment_dir_path)
+    # Only create deployment file if it doesn't exist (preserve cluster ID on sync)
+    deployment_file_path = deployment_dir_path.joinpath(constants.deployment_file_name)
+    if not deployment_file_path.exists():
+        _create_deployment_file(deployment_dir_path)
     # Copy any config varibles from the spec file into an env file suitable for compose
     _write_config_file(spec_file, deployment_dir_path.joinpath(constants.config_file_name))
     # Copy any k8s config file into the deployment dir
@@ -481,16 +491,16 @@ def create_operation(deployment_command_context, spec_file, deployment_dir, extr
     # Copy the pod files into the deployment dir, fixing up content
     pods = get_pod_list(parsed_stack)
     destination_compose_dir = deployment_dir_path.joinpath("compose")
-    os.mkdir(destination_compose_dir)
+    os.makedirs(destination_compose_dir, exist_ok=True)
     destination_pods_dir = deployment_dir_path.joinpath("pods")
-    os.mkdir(destination_pods_dir)
+    os.makedirs(destination_pods_dir, exist_ok=True)
     yaml = get_yaml()
     for pod in pods:
         pod_file_path = get_pod_file_path(stack_name, parsed_stack, pod)
         parsed_pod_file = yaml.load(open(pod_file_path, "r"))
         extra_config_dirs = _find_extra_config_dirs(parsed_pod_file, pod)
         destination_pod_dir = destination_pods_dir.joinpath(pod)
-        os.mkdir(destination_pod_dir)
+        os.makedirs(destination_pod_dir, exist_ok=True)
         if opts.o.debug:
             print(f"extra config dirs: {extra_config_dirs}")
         _fixup_pod_file(parsed_pod_file, parsed_spec, destination_compose_dir)
@@ -509,7 +519,7 @@ def create_operation(deployment_command_context, spec_file, deployment_dir, extr
         # Copy the script files for the pod, if any
         if pod_has_scripts(parsed_stack, pod):
             destination_script_dir = destination_pod_dir.joinpath("scripts")
-            os.mkdir(destination_script_dir)
+            os.makedirs(destination_script_dir, exist_ok=True)
             script_paths = get_pod_script_paths(parsed_stack, pod)
             _copy_files_to_directory(script_paths, destination_script_dir)
         if parsed_spec.is_kubernetes_deployment():
diff --git a/stack_orchestrator/deploy/webapp/deploy_webapp.py b/stack_orchestrator/deploy/webapp/deploy_webapp.py
index 0353ad16..cdd07481 100644
--- a/stack_orchestrator/deploy/webapp/deploy_webapp.py
+++ b/stack_orchestrator/deploy/webapp/deploy_webapp.py
@@ -91,6 +91,7 @@ def create_deployment(ctx, deployment_dir, image, url, kube_config, image_regist
         deploy_command_context,
         spec_file_name,
         deployment_dir,
+        False,
         None,
     )
     # Fix up the container tag inside the deployment compose file
diff --git a/tests/database/run-test.sh b/tests/database/run-test.sh
index 405f6d34..2b68cb2c 100755
--- a/tests/database/run-test.sh
+++ b/tests/database/run-test.sh
@@ -86,7 +86,7 @@ fi
 echo "deploy init test: passed"
 
 # Switch to a full path for the data dir so it gets provisioned as a host bind mounted volume and preserved beyond cluster lifetime
-sed -i "s|^\(\s*db-data:$\)$|\1 ${test_deployment_dir}/data/db-data|" $test_deployment_spec
+sed -i.bak "s|^\(\s*db-data:$\)$|\1 ${test_deployment_dir}/data/db-data|" $test_deployment_spec
 
 $TEST_TARGET_SO --stack ${stack} deploy create --spec-file $test_deployment_spec --deployment-dir $test_deployment_dir
 # Check the deployment dir exists
diff --git a/tests/deploy/run-deploy-test.sh b/tests/deploy/run-deploy-test.sh
index c18c5cb0..5cafd689 100755
--- a/tests/deploy/run-deploy-test.sh
+++ b/tests/deploy/run-deploy-test.sh
@@ -85,6 +85,7 @@ else
     exit 1
 fi
 $TEST_TARGET_SO --stack test deploy down --delete-volumes
+
 # Basic test of creating a deployment
 test_deployment_dir=$CERC_REPO_BASE_DIR/test-deployment-dir
 test_deployment_spec=$CERC_REPO_BASE_DIR/test-deployment-spec.yml
@@ -122,6 +123,41 @@ fi
 echo "dbfc7a4d-44a7-416d-b5f3-29842cc47650" > $test_deployment_dir/data/test-config/test_config
 
 echo "deploy create output file test: passed"
+
+# Test sync functionality: update deployment without destroying data
+# First, create a marker file in the data directory to verify it's preserved
+test_data_marker="$test_deployment_dir/data/test-data-bind/sync-test-marker.txt"
+echo "original-data-$(date +%s)" > "$test_data_marker"
+original_marker_content=$(<$test_data_marker)
+# Also save original spec content to compare
+original_spec_content=$(<$test_deployment_spec)
+
+# Modify spec file to simulate an update
+sed -i.bak 's/CERC_TEST_PARAM_3:/CERC_TEST_PARAM_3: FASTER/' $test_deployment_spec
+# Run sync to update deployment files without destroying data
+$TEST_TARGET_SO --stack test deploy create --spec-file $test_deployment_spec --deployment-dir $test_deployment_dir --sync
+# Verify the spec file was updated in deployment dir
+updated_deployed_spec=$(<$test_deployment_dir/spec.yml)
+if [[ "$updated_deployed_spec" == *"FASTER"* ]]; then
+    echo "deploy sync test: spec file updated"
+else
+    echo "deploy sync test: spec file not updated - FAILED"
+    exit 1
+fi
+# Verify the data marker file still exists with original content
+if [ ! -f "$test_data_marker" ]; then
+    echo "deploy sync test: data file deleted - FAILED"
+    exit 1
+fi
+synced_marker_content=$(<$test_data_marker)
+if [ "$synced_marker_content" == "$original_marker_content" ]; then
+    echo "deploy sync test: data preserved - passed"
+else
+    echo "deploy sync test: data corrupted - FAILED"
+    exit 1
+fi
+echo "deploy sync test: passed"
+
 # Try to start the deployment
 $TEST_TARGET_SO deployment --dir $test_deployment_dir start
 # Check logs command works
diff --git a/tests/external-stack/run-test.sh b/tests/external-stack/run-test.sh
index 084f3b9d..de89f645 100755
--- a/tests/external-stack/run-test.sh
+++ b/tests/external-stack/run-test.sh
@@ -125,6 +125,49 @@ fi
 echo "dbfc7a4d-44a7-416d-b5f3-29842cc47650" > $test_deployment_dir/data/test-config/test_config
 
 echo "deploy create output file test: passed"
+
+# Test sync functionality: update deployment without destroying data
+# First, create a marker file in the data directory to verify it's preserved
+test_data_marker="$test_deployment_dir/data/test-data/sync-test-marker.txt"
+mkdir -p "$test_deployment_dir/data/test-data"
+echo "external-stack-data-$(date +%s)" > "$test_data_marker"
+original_marker_content=$(<$test_data_marker)
+# Verify deployment file exists and preserve its cluster ID
+original_cluster_id=$(grep "cluster-id:" "$test_deployment_dir/deployment.yml" 2>/dev/null || echo "")
+# Modify spec file to simulate an update
+sed -i.bak 's/CERC_TEST_PARAM_1=PASSED/CERC_TEST_PARAM_1=UPDATED/' $test_deployment_spec
+# Run sync to update deployment files without destroying data
+$TEST_TARGET_SO_STACK deploy create --spec-file $test_deployment_spec --deployment-dir $test_deployment_dir --sync
+# Verify the spec file was updated in deployment dir
+updated_deployed_spec=$(<$test_deployment_dir/spec.yml)
+if [[ "$updated_deployed_spec" == *"UPDATED"* ]]; then
+    echo "deploy sync test: spec file updated"
+else
+    echo "deploy sync test: spec file not updated - FAILED"
+    exit 1
+fi
+# Verify the data marker file still exists with original content
+if [ ! -f "$test_data_marker" ]; then
+    echo "deploy sync test: data file deleted - FAILED"
+    exit 1
+fi
+synced_marker_content=$(<$test_data_marker)
+if [ "$synced_marker_content" == "$original_marker_content" ]; then
+    echo "deploy sync test: data preserved - passed"
+else
+    echo "deploy sync test: data corrupted - FAILED"
+    exit 1
+fi
+# Verify cluster ID was preserved (not regenerated)
+new_cluster_id=$(grep "cluster-id:" "$test_deployment_dir/deployment.yml" 2>/dev/null || echo "")
+if [ -n "$original_cluster_id" ] && [ "$original_cluster_id" == "$new_cluster_id" ]; then
+    echo "deploy sync test: cluster ID preserved - passed"
+else
+    echo "deploy sync test: cluster ID not preserved - FAILED"
+    exit 1
+fi
+echo "deploy sync test: passed"
+
 # Try to start the deployment
 $TEST_TARGET_SO deployment --dir $test_deployment_dir start
 # Check logs command works