Legal Question in Family Law in Texas

I assume that you have a court order giving you "custody" of your son. Are your parents part of that court order; in other words, are they parties to the case? If so, then you should file to enforce the order. You should also expect that they may counter-sue you and try to make themselves the primary conservators. If they are not part of the case, then you should report them to the police or try to get the police to accompany you to get your child. The police are often reluctant to get involved and, if this is the case, then you should ask the court to order them to return the child to you. Again, this might make them sue for "custody" of the child.