diff --git a/stack_orchestrator/deploy/deployment_create.py b/stack_orchestrator/deploy/deployment_create.py
index 601f6c77..6b049fda 100644
--- a/stack_orchestrator/deploy/deployment_create.py
+++ b/stack_orchestrator/deploy/deployment_create.py
@@ -465,7 +465,10 @@ def init_operation(
             else:
                 volume_descriptors[named_volume] = f"./data/{named_volume}"
         if volume_descriptors:
-            spec_file_content["volumes"] = volume_descriptors
+            # Merge with existing volumes from stack init()
+            # init() volumes take precedence over compose defaults
+            orig_volumes = spec_file_content.get("volumes", {})
+            spec_file_content["volumes"] = {**volume_descriptors, **orig_volumes}
         if configmap_descriptors:
             spec_file_content["configmaps"] = configmap_descriptors