I have a question about legally changing my daughters last name. My daughter is currently 2 years old and her last name is hyphenated with her fathers last name and mine. He is not listed on the birth certificate and has had no contact with her since she was a week old. I do not receive child support and don't know exactly where he is. He is an undocumented illegal mexican. I am a us citizen. I am currently living in the state of Washington and want to change her last name to mine. She was born in the state of Texas. I have read the rules on name changing in Washington State and Texas which are both the same. My question is will the fact that not knowing where he is affect the proceeding of the name changing and do I have to get a lawyer?