she is young and sounds like he is trying to play, but playing with her teeth on a child is unacceptable. I would recommend working on her sit/stay and leave it command without distractions first. Allowing her near trampoline would be a big distraction that you would have to work up to. It sounds like she is overstimulated when then the kids are jumping on trampoline so I wouldn't allowed her there until she could handle it without acting like that. Let her watch from the inside and treat when she is being good and work your way up. We had to do this when our kids were in the pool. As soon as our dog started running and barking while kids were splashing, dog was brought to the house and put in a down (he could still see them, but wasn't so close that he was bananas) Then, overtime I let him get closer and closer as long as he didn't bark. Now he is able to go out with them and he will hang out by the edge without losing his mind. I still let him walk/run around it, but if he barks...he comes back in. With consistency, she will get the idea of what you expect. It took about a week for this training to be effective for our 6 month old.
As for leave it, we have a 10 year old daughter and she knows now if she is walking with her stuff animal, and Samson focuses on it, she says "leave it" and the dog walks off. That is because I have been training since we got him at 8 weeks on the leave it command. I think it is so important! Tons of videos you can find if you don't have a trainer. In the meantime, control the amount of freedom she has by always keeping her on a lead. Our 6 month old has a long drag lead on him all day long even in the house. I can control easily what he is allowed to touch, nip, play with etc.
You'll get there, but give her rules so she learns her boundaries. Good luck!