Legal Question in Family Law in Texas

When you say "lost his parental rights" I assume that you mean that a Court order was signed that terminates Dad's parental rights.

If that is the case, he is legally a stranger to the children - just like I am. If I wanted to see your children, and you thought it wouldn't harm them, you could say "yes" or you could say "no."

You can't absolutely control whom your children talk to or associate with - if Dad is sitting at the next table in a restaurant, he may talk to them.