We had a girl named Pete for the same reason! Her Daddy had her before I met him and his friend, who he got her from, said she was a boy. He took Pete in to get fixed and found out Pete was actually a girl and just kept her name.
This is such a hard road to have to navigate. We lost out 13 year old back in February to GI Lymphoma after going through and trying to navigate these same problems. I don't have any helpful advice, as we only used the chlorambucil for about two weeks giving it Monday, Wednesday and Friday...
This one isn't, I didn't meet her daddy until she was about 6 or 7, so when we got this munchkin I bought new clothes for her. I did save all of big sisters clothes and costumes for when she's bigger. Her sister wasn't too impressed with mom dressing her up 😁