I have a range of ages at my house. The humans are 17,13,9, and 7. The non humans are 9,3, and 14 weeks. The 17yr old is scared of the puppy and runs away shrieking, which my pup thinks is a super fun game, and she will keep chasing and biting. My younger girls (the older ones are my stepdaughters), know better because they’ve always had dogs around them since birth. Is any mouthing, nipping, jumping, etc happens, the turn their backs to the dog and ignore them. I’ve found this method a whole lot easier than doing physical corrections. The dog learns quickly that when they get “bitey” the human shuts down and they get nothing. No pets, no rubs, no treats or toys (if they will not redirect to the toy) and no attention paid to them at all. So there is no fun or reward in them acting that way.
My 3yr old Husky GSD mix is VERY mouthy with my husband, because that is how they play. But the dog knows it’s okay to play with dad that way, and no one else. He has never nipped or mouthed the kids.
I’m in the process of training my husband that he cannot play in certain ways with the puppy. He thinks it’s adorable when the puppy nibbles his ear (yuck and yuck again). I have to remind him over and over that any behavior he allows her to get away with as a puppy (because it’s so cute when a puppy does it) she will carry into adulthood thinking it’s an acceptable behavior. I asked him if he wanted a 60lb dog nibbling his ear, and of course, he said no. So now he corrects her when she does it (at least when I’m around, I have a feeling he lets her do it when I’m not) so he doesn’t end up losing an ear when she matures.
My point, your dog was likely allowed to do this as a puppy, because she was so cute, and it’s a puppy thing. And she then carried the behavior into maturity. So you’ve got some training to do on your hands, for both the humans and dog. Teach your kids to try to redirect with a toy, and if that doesn’t work, to give the dog their back, and refuse to interact with her at all. She will learn it’s no longer fun to mouth the kids. And you need to supervise any and all time the dog spends with the kids so you can verbally (with, or without a physical correction with an e-collar or prong collar) correct her when she is trying to be mouthy with the kids. But it’s just as important that the kids are trained as it is that the dog is trained.