My question involves name change laws in the State of Washington
My child was given my last name at birth and I am the custodial parent. The father (biological, we are unmarried) signed the birth certificate at the time with no issues. The child is now entering school and the father wants to change the child's last name to be hyphenated.
For personal reasons, and for paperwork reasons (schools and medical), I would like the child to maintain his given name; I suggested the child may change the last name as desired (hyphenated or otherwise) when the child turns 18. The father used the same argument when pushing changing the last name now.
Do I have any ground to stand on with this issue?
Thanks!

