Hi captainwil,
We see you're having issues moving a child account to a new Family Sharing group, and we'd be happy to help.
First, be sure that all steps/suggestions from this page are followed when trying this process: Move a child to another group using Family Sharing
Ensure that both the current and new Family Organizers have their country/region set correctly, and have a valid payment method on file.
If that looks OK, have the new Organizer look for the transfer request in Settings > Family Transfer Request (would show up immediately below their name at the top of Settings, if so).
It's possible they may also receive an email to an account associated with their Apple ID, so be sure to have them check any applicable email accounts, including the spam/junk folders for each.
If the issue still persists, we'd recommend reaching out directly to Apple Support for further investigation: Get Support
Take care!