Hi and welcome to YT
.
Given your family's inexperience, I'm *very* concerned over this tiny, tiny young one being with you. This puppy should not have been taken from its Momma yet - it's too young....WAY too young. Yorkie puppies should be kept with their Momma's until they are twelve weeks old, not only a wee 6 weeks.
So, let me stress...you're in a very precarious situation here that could put this puppy's life in danger. I hope you truly understand this.
Most importantly right now, please find some tiny sweaters to keep him warm. And/or cut up a tube sock and cut 2 holes in it for his front legs and use that for warmth.
Hypoglycemia is a real danger for yorkie puppies, and if that's what's going on when he is shaking - it needs to be treated IMMEDIATELY with Nutrical or Karo syrup, or he could die.
Please get this puppy to the Vet ASAP to be fully checked out and to receive proper medical advice.