My son had 1 more fighter related question. He wants to fly from an contested territory to an enemy territory to initiate a battle. I told him no unit could do that, exit a contest to start a new fight, but he wanted an official ruling for fighters.
alexstrov; page 19 the next to last paragraph says if you are attacking in a contested territory and eliminate the defender and survive, you get control. If you both die, your buddy in there gets it if they are the only power left. If multiple allies are left, they are to decide amongst themselves. If they can’t YOU decide. Precisely who “you” are is not clear. It could be the defender that was eliminated, or the owner of the game. I think it is the first, but Krieghund can say for sure when he gets here.
Otherwise it sounds like you got multinationals figured out, yes Britian can jump in, the more the merrier. They can chose to reinforce you and not attack. Or they can wait until you have all but 1 or 2 enemy left, attack and kill them and claim the territory.