diff --git a/unilabos/registry/devices/liquid_handler.yaml b/unilabos/registry/devices/liquid_handler.yaml
index f827855..d8c05a5 100644
--- a/unilabos/registry/devices/liquid_handler.yaml
+++ b/unilabos/registry/devices/liquid_handler.yaml
@@ -6847,7 +6847,10 @@ liquid_handler.prcxi:
         type: LiquidHandlerPickUpTips
       set_liquid:
         feedback: {}
-        goal: {}
+        goal:
+          liquid_names: liquid_names
+          volumes: volumes
+          wells: wells
         goal_default:
           liquid_names:
           - ''
diff --git a/unilabos/registry/devices/work_station.yaml b/unilabos/registry/devices/work_station.yaml
index 9dd6c96..564d49c 100644
--- a/unilabos/registry/devices/work_station.yaml
+++ b/unilabos/registry/devices/work_station.yaml
@@ -240,6 +240,8 @@ workstation:
           type: object
         type: AGVTransfer
       AddProtocol:
+        placeholder_keys:
+          vessel: unilabos_resources
         feedback: {}
         goal:
           amount: amount
diff --git a/unilabos/resources/graphio.py b/unilabos/resources/graphio.py
index 956e7fb..a392438 100644
--- a/unilabos/resources/graphio.py
+++ b/unilabos/resources/graphio.py
@@ -461,7 +461,6 @@ def resource_plr_to_ulab(resource_plr: "ResourcePLR", parent_name: str = None):
             "data": all_states[d["name"]],
         }
         return r
-
     d = resource_plr.serialize()
     all_states = resource_plr.serialize_all_state()
     r = resource_plr_to_ulab_inner(d, all_states)
diff --git a/unilabos/ros/nodes/resource_tracker.py b/unilabos/ros/nodes/resource_tracker.py
index 10cc4bc..e6054ef 100644
--- a/unilabos/ros/nodes/resource_tracker.py
+++ b/unilabos/ros/nodes/resource_tracker.py
@@ -10,6 +10,15 @@ class DeviceNodeResourceTracker(object):
         self.resource2parent_resource = {}
         pass
 
+    def prefix_path(self, resource):
+        resource_prefix_path = "/"
+        resource_parent = getattr(resource, "parent", None)
+        while resource_parent is not None:
+            resource_prefix_path = f"/{resource_parent.name}" + resource_prefix_path
+            resource_parent = resource_parent.parent
+
+        return resource_prefix_path
+
     def parent_resource(self, resource):
         if id(resource) in self.resource2parent_resource:
             return self.resource2parent_resource[id(resource)]