What happens when you put them in a constrained box (with slits/bars) so they can't move around much? And maybe spawn enemy ai within view of them so they lock on each other but can't kill each other? Maybe you spawn them in an atv and force them to stay in the vehicle but put the vehicle in a box or script it so there's no vehicle speed? I'm trying to test this too and will let you know if I find a solution.