Cutie!
Sounds like the son is learning the joy of "consequences": you get excited = puppy gets excited = puppy uses mouth on you / you push puppy away = puppy pushes back in... (dogs have strong "opposition reflexes"... you push or pull one way, and they will instinctually oppose it)
If you sit down with the kids, can you help them see the logic in "consequences"?
Have them try whispering to the dog... and see how much better that works than yelling...
Have them try giving a command ONCE and then remain silent, and see how much better that works than repeating a command over and over again (this might have to wait until the puppy knows the commands better)
Definitely have them help with training, meal-times, teaching tricks, going for walks, etc.
And, as you mentioned, anytime puppy gets over-excited and wants to use her mouth... get OFF the floor and out of the room (calmly).
Puppy Zen: "You must give up the treat, to get the treat" (in this case, playtime with the kids is the 'treat')