Set 'Mark' parameter by room number for dynamically connected elements in different host levels

I am trying to change the ‘Mark’ parameter for heating coils according to the room number that they serve. The heating coils are on a different host level, and aren’t necessarily directly above the room that it serves’ floor area.

My diffusers are hosted in a linked revit model while my heating coils and all ductwork are hosted on ‘Level 2’.

My current best approach to this problem is to find the room number associated with each diffuser, which I have been able to do using;

Note: The node ‘FamilyInstances.Space’ is from the Rhythm package.
Currently all this dynamo script does is get the space number of each air terminal.

For simplicity sake I have been able to apply the space number to the ‘Mark’ parameter for each diffuser. I would like to then pass this information along the ductwork that connects the diffusers to their respective heating coil.

I have not been able to find a node, or way to select elements that are connected to my diffusers. I think if I was able to select the connected elements I would be able to pass my room number along to the first heating coil upstream.
If you have any ideas how to do this, or have seen it done before - I would appreciate the help.

*New users cannot upload attachments - will upload dynamo file and revit example if/when I can.
Thanks in advance!

Check out the MEPover package. It has nodes for connected elements. You could also try getting the mechanical system of the terminals and each coil and compare that way.