What are you asking exactly? I can't quite follow.
The trainer is not going to fix the problem of the dog jumping and mouthing. You have to fix that. And you have to do it, like Bailif said, by changing how you live and interact with your dog. Whatever you (or your kids) are doing now is rewarding the behavior; that's why it isn't going away.
What the trainer should be doing is teaching you what you're doing wrong right now, and what you should do to decrease the behaviors you don't want and increase the behaviors you do want.
After that it's up to you to follow through by changing your own behavior accordingly and being consistent with those changes. If you don't do that, the program will fail.
This is one of those issues that's really really easy to fix with the dog but sometimes impossibly difficult to fix on the human end of the leash.
ARCHMX TDCH Pongu the Insane, CD-C, RE, RL1X6, RL2X5, RL3X2 (GSD mix, b. Apr 2010)
Crookytail the Tigerwuff, RL1, ITD (Akita mix, b. Jan 2011)