Legal Question in Family Law in Texas

To properly answer your question I would need much more information. How many years is "90% of her life." Why was she in your home so much? Why can't you see your granddaughter during your son's possession time?

I can think of several answers to those questions that would completely change the answer as to your rights. That being said, generally grandparents do not have specific rights. A fit parent has the right to control the child's life as he or she desires unless there is a physical or emotional threat to the child.