Anyone else think of
? Certainly one technique for the kids is on display there, grabbing clothes.
I'd say the training for the kids would have to focus on swarming, tripping and jumping on the adult with special attention paid to stomping on your head once you are down. Probably motivate the kids with something like "A bad man who killed your mommy and daddy is going to be in this room. No matter how many of you he hurts it's very important for you to take him down so he doesn't kill anyone else's mommy or daddy." If you've been knocked down and the kids pile on you it's over.
Personally I have a VERY high tolerance for pain and more than 5 years of martial arts training so I'd go with 50+.