First: A dog should never be punished for growling. It's a warning that somebody is doing something that makes the dog uncomfortable. If you manage to "train" her not to growl, she'll just skip straight to snapping. Nobody wants that.
Second: You need to somehow persuade your sister not to get in her face. If she persists, she will get bitten and it's the dog that will truly suffer.
Getting her to accept your sister will require great patience and, likely, the help of a trained canine behaviorist (not just a trainer.) It will take time and cost money and I sense that you're not in a position to make the decisions regarding those things.
I applaud your family for trying to help this poor dog. You have a hard road ahead of you.
I hope anyone considering buying a dog from a puppy mill/pet store will read this and understand that this is what happens to the breeding stock.
Second: You need to somehow persuade your sister not to get in her face. If she persists, she will get bitten and it's the dog that will truly suffer.
Getting her to accept your sister will require great patience and, likely, the help of a trained canine behaviorist (not just a trainer.) It will take time and cost money and I sense that you're not in a position to make the decisions regarding those things.
I applaud your family for trying to help this poor dog. You have a hard road ahead of you.
I hope anyone considering buying a dog from a puppy mill/pet store will read this and understand that this is what happens to the breeding stock.