My question involves name change laws in the State of: Texas. I have been divorced for 4 years and had 3 children. The biological father relinquished his rights and is not a part of their life. I've been remarried for 3 years and my children want to have my last name. In school and sports they use my last name. What is the best way to change their name and do I need their biological's father consent? About how much does it cost?