Scenario A: At this time, you can only convert a registration fee into a donation.

Scenario B:
  1. Navigate to Communities > Special Events > Friends Asking Friends > Kintera Thon
  2. Hover over Event Name and select Bookkeeping
  3. Click Manage Initiative Records
  4. Beside Search For, select Participants
  5. Locate your participant and click Edit beside their name
  6. Click Convert Registration to Donation
Alternative Solution for Scenario A: Create a Sphere-only registration type and register the donor for the event through Bookkeeping on the back-end.