I do wonder if you are trying to make it too complicated.
Would it not be simpler to have a few options, such as mercs on patrol, mercs on defense, or mercs on fleet/formation/wingman duty?
You simply get a merc or however many of them that join your squad and follow broadcasts. Simple, easy and most of the backend is already there.
You would need a way to keep them flying with you, so formations for members in fleet would be a way to resolve that.
This would also be a good way to implement a fleet formation setup, as it stands we have nothing and that’s pretty stupid for a space game.