I can’t remove my daughter from my family sharing account

Sorry for the long question… a few years ago I set up family sharing for iCloud storage. My then 10 year old was using an old laptop and we set her up with a iCloud email address. Fast forward a few years and we have realised my husband and I are both paying for extra iCloud storage so need to all move over to his family sharing and close mine. Everyone else in the family has moved but I can’t seem to remove my daughter from my account. Somehow over the years she has a new iCloud email and is now in the new family account that my husband had set up but her old email is still in my family sharing and I can’t get rid of it. I can’t join the new family account as it tells

me I’m in another family.

I have tried deleting all her contacts details from my phone and turning it off but the old email is still there.

Any help appreciated.

[Re-Titled by Moderator]