1. Go to Communities > Special Events > Friends Asking Friends > Kintera Thon
  2. Hover over your event and select Bookkeeping
  3. Click Manage Initiative Records
  4. Search for the participant
  5. Click Edit
  6. Select the Edit Registration Information tab
  7. Select the appropriate t-shirt size
  8. Click Save
Please Note: This can also be managed through the Participant's HQ via the Edit Profile option.