My question involves name change laws in the State of: WI

Hi,
In 2006 my daughter was born to my then girlfriend. After she was born I found out that she had given my daughter her last name on the birth certificate rather than mine. I am listed on the BC as the father. My ex and I were granted joint custody along with 50/50 placement. My ex is now married and has changed her last name to her husbands. Now my daughter has neither of our last names. If I take her to court do I have a good chance of getting her name switched over to mine?? I realize I probably should have attempted to change it years ago.
Thanks