Family Registrations can only be entered through the front end of the event, and not through the back end via Bookkeeping>Registration Entry or Manage Initiative Records. In the backend of the event, an existing individual can only be moved to an existing family via Bookkeeping > Manage Initiative Records or join an existing family via Bookkeeping>Registration Entry.

The individual participant will need to be deleted from the event, and re-register on the event's front end as a family registration.