My question involves name change laws in the State of: texas
My girlfriend and I are wanting to get married but one thing we want to know is if we can change her kids last names to mine. She has legally adopted these kids and changed there names then to hers since we were not together for that long. But now since we have been together for a while and I am the only father figure they know and love them as if they were my own she wants them to have my last name when we get married. She has herd that I would have to adopt them to change there names its not that I don't want to its just that it cost 4000 per child for her to do it and that would come out to 12000 and we can't afford that. So can I change them with out adopting them

