Is there no way to change date of birth for under 13

I created an apple ID for my daughter when we first got her an apple device 11 years ago. When I created I didn't put her actual information in there because I didn't think anyone need to know when my daughter's actually birthday was and that it would matter. Now she is 18 and shows up as an 8 years old and in some cases can't do things because her account is considered a child account.

Is there absolutely no way to update her DOB for someone under 13?

Can we remove that account from family, create a new account and add it to family share?