Legal Question in Family Law in Texas

Nothing, the court and police can only enforce court orders and in this case there are none. Your son has to go to court to get his rights to visitation in a court order that then can be enforced. Paternity does not automatically give you rights to a child against the child's other parent, only against a non-parent. If your son feels like his daughter is in danger then if the daughter was at daycare or any other place where the mother was not, then your son can go and pick her up. However, I caution doing this sort of thing because the child's best interests need to be put first, not the parent's, and using the child like this could be damaging to her. So, the best action is to make sure that she is safe even if he can't see her and then hire an attorney to get his rights on paper.