Can I change my child's last name to match my own in Michigan? I have sole legal & physical custody of my 6 year old. Her father & I were never married but she has his last name. He has had no contact with her for 2 years but he has intermittently paid some child support (in the sense that the state automatically deducts it from his paychecks when he gets a job). Do I still need his permission to change it?