Legal Question in Family Law in Washington

I would say that on its own, the document purporting to give your friend's mother your friend's parental rights is not valid since your friend was a minor at the time that she signed it, and did so without an independent guardian who could represent her in such a proceeding. You did not mention how many years have passed since this document was signed, and you don't mention who has actually been raising the child throughout this time. Without that information, it is hard to know what a court would do if your friend decided that she wanted to challenge her mother to become the primary custodial parent for her own child.

As a third-party, meaning people who are not the biological parents of a child, the grandmother has very little rights unless she could prove that both of the biological parents are "unfit parents" such that she would be justified in bringing a "third-party custody petition" to try to officially become the child's custodial caregiver. It becomes a very fact sensitive analysis for an attorney and later the court when deciding what to do.

At this point, the best thing that your friend can probably do is to consult with a local attorney for an hour, even if she has to pay for the hour, so that she may obtain an informed legal opinion based on all the facts of the case which the lawyer will go through with them. From there, assuming that your friend has a good case, in my opinion, a good lawyer will first approach her mother and try to negotiate something, and only if that fails to yield a positive result will they consider going to court, which will inevitably become a very expensive proposition because cases like this are never easy or cheap.

Best of luck to you and your friend.