What is the name of your state (only U.S. law)? North Carolina
What would be the repercussions if my daughter came home to pennsylvania with my granddaughter to live before the divorce.
Before the divorce is filed or before it is finalized?
If the divorce has not been filed, she is free to go whereever she wants. HOWEVER, her husband could (and probably would) file for divorce in NC and would ask the judge for temporary custody because of the wife's attempt to take the daughter away. This would reflect badly on her.
If the divorce has already been filed, then read the court documents. The judge may have given temporary orders allowing her to move (or forbidding her from moving) with the child. If there are no specific orders, then read the court's default orders which apply to everyone. Typically, one would not be allowed to move a minor child out of the jurisdiction of the court.
The best option is to file for divorce there and work out a final agreement with the court settling all the divorce matters and allowing her to move with the child.
Second best is to file for divorce and ask for (and receive) temporary orders allowing her to move with the child. In either of those cases, she needs to demonstrate why it is in the child's best interest to be moved away from her father, friends, school, home, etc. That can be done, but she must not assume that just because she's the mother, she's going to get to take the child.
If she moves without the court's permission, she's likely to have a world of headaches (unless her stbx just doesn't care about the daughter - but even then, he may use custody as a weapon to make her life miserable).
