Participants can be registered for a TeamRaiser on the back-end in the back end but not the front end if the event status is set to only Accepting Gifts Only. To set this status:
  1. Go to Fundraising > Select TeamRaiser
  2. Click edit for the TeamRaiser event
  3. Select Publish 
  4. Select "Accepting Gifts Only" under 1. Status
  5. Click Finish