Okay, I tried a quick version with a unit called squad_leader, with a size zero and the ability to summon pet squad_member. The enemy won't attack the leader because it's size zero, but it will try. They will even surround it and block it in so it can't go anywhere, which is weird because it can go right through trees but not units. Go figure. Anyway, the main problem was that the pets don't automatically follow the leader, which I thought they were supposed to do. There might be a way to get it to work better, but that's all I found with my maybe five minutes of work.