Hi Jill Worship
You could try:
- Check Microsoft Family and cancel any pending invitations, then re-send them.
- Confirm the invitees have completely left any previous Microsoft Family group before accepting a new invitation.
- Try sending a sharing link instead of an email invitation, and have the recipient accept it in an InPrivate/Incognito window.
- If you already have several pending invites, wait for those to be accepted or cancelled before creating additional invitations. Microsoft 365 Family can be shared with up to five other people.
If the error persists for more than 24-48 hours, it's likely a backend account-sharing issue that only Microsoft Support can investigate, especially if you're receiving a Trace ID with the error, since it's out of the public forum's ability.