Hi Jastect,
In order to edit an Child Apple Id you can just go to https://appleid.apple.com/ and log as your daughter and edit all data (except id itself and birthdate). This is possible only if you know the password :-) even without knowing, the recovery procedure is working fine.
In my case:
- I created an Child apple ID (as described in Family Sharing and Apple IDs for kids), child is -13y
- As mentioned in Leave Family Sharing : "Children under 13 can't be removed from a family. If you need to, you can transfer the child to another family or delete their Apple ID". ok, fair enough. Then I want to delete the id... But I cannot find where the delete option is available ???
Hopefully someone can help.