Add incoming AOG's to existing AD's

[Mehring]

Having just puzzled over and nearly posted in the tech forum over why, for two turns, an AOG I transferred to an HQ wouldn't fly in an AD with the rest of the units under the same HQ, I finally figured I had to remove the entire HQ from the AD and add it again, so the AOG I'd transferred it to, would fly with it. Would be much simpler if this were not necessary.