I didn't see anything that said the OP recently had a litter (possible I missed it in her posts...) But, if your father's best friend is a vet, wouldn't it be in the best interest of the dog for your mother to turn her over to him for help? After all, you really don't have a good history on this dog and you don't know what problems she might have. 3 seems to be a little young to have had to have all her upper teeth removed unless there was some other underlying problem.
And just because the original owner said they are 100% sure the father is another yorkie doesn't mean it's true. If they left her out in the backyard, even briefly, it could be the neighborhood Casanova through the fence...
__________________ Don't get your knickers in a knot. Nothing is solved and it just makes you walk funny.  |