Drag and Drop Mechanics

[Homer S]

I'm doing a proof of concept for 40K Battle-forged armies. This type of army requires 1 to unlimited Detachments and each unit must be in a Detachment. Sounds like a drag and drop to me. I can require the army to have at least one Detachment based on tags and rules. I can tag a top level unit which is dropped into a Detachment via the "runtime.multiple" tag.

Here is where it gets messy. I would like the dropped unit to tag the Detachment based on the unit's FOC tag (e.g., Group.HQ). How can I do this? I'm thinking it is context related and it is not "parent".

Also, when dropping is it possible to specify that the Detachment always appears first?

I keep getting these mixed up when dragging and dropping:

Combined Arms Detachment
Autarch

Autarch
Combined Arms Detachment

Homer