Family sharing - how to transfer child account

Im trying to move a child account to another family sharing organizer. I followed the directions, the other adult invited the child. I’m supposed to get a notification to approve the transfer. However, I never received the notice, and the child can’t join because he’s already part of another family. It says he has to leave current family sharing plan but there is no way to move him. Very annoying. Any suggestions on how to get the notification to approve the transfer?