Well I have some good news and some bad news
.... The good news is that >>>> You have a Yorkie Puppy
and the Bad News is that >>>> You Have A Yorkie Puppy
The growling is typical and it can get Very vocal
it's just their form of play and they love Tug of War ..... My guys would love to play all day long pulling them back and forth across the room
Don't worry too much about being rough about pulling them
let them be the judge on the strength you pull them
Nipping ... is another thing you need to address
They need boundaries ..... mouthing or nipping is a problem some times with these dogs
and it can lead to aggression
I'm not surprised that the youngest ones in your family are getting the brunt of it
you need to tell them not to allow nipping ... children will be the ones who like to play rough with the puppy and this leads to the puppy nipping more
when the puppy nips ... it's UH! and he goes into solitary
that needs to be law
you never want to allow that behavior esp with children in the house