I have been married for four years, and my 10 yr old desperately wants to change his last name (which is my maiden name) to ours. My son has never met his bio. Father, and never wants to. The feeling is mutual on his bio. Father end too. He did sign the birth certificate for whatever reason? How can I do this simply and cheaply? I want my son to be happy, he feels left out, and that makes me feel really bad as a parent.