Stopping the game has already been addressed, so let me just throw out a potentially even more courteous suggestion. When you get that opportunity to address the problem with the head coach, don't give him a directive, involve him in solving your problem.
"Coach, I need your help. I can't have assistants up off the bench during play. Can you help me with that, please?"
As for the fact that the asst. is the super's hubby, isn't it really just too sad that even (self)important people have to follow the rules?
But in discussing it with the AD, who obviously feels some amount of pressure from his boss' boss, try to get the AD on your side: "I'm sorry it had to come to that, but we both know he can't be up like that. He's putting us both in a tough spot." Of course, not stopping the game, which has the unwanted effect of singling him out for unwanted attention, should help too.
No solution works every time or for every official. But if you can bring the coach or AD over to your side, form a little two person team to solve your collective problem, or at least get them to feel that it's yours and his collective problem even if you can't fix it, that person is more likely to respond positively than if it's mano a mano.
Just my $0.02