I agree your right, the owners will complain their dog is being stolen but I don’t think there’s anything wrong with “stealing” an abused dog. Maybe it isn’t physical abuse but it is still abuse. JadeFarms is taking this dog out of the abuse of neglect, and giving it a safe place to give birth to puppies that will hopefully have a better future.If you keep the dog confined to a safe place to have her puppies, there's a chance the owners may complain that you "stole" their dog.
But if you set up a safe place where she can freely come and go, and she chooses to have puppies there, then it's really their fault for not keeping the dog home.
And depending on how observant the neighbors are--if they say she's not pregnant, and if she has the puppies on your property, they may never even know about the puppies unless you tell them. (Whether to tell the neighbors would be a decision for yourself and your parents.)
I fully agree though, that the owners are responsible for letting the dog come to OP and allowing that to happen.