This is done by doing a partial or whole refund but not actually refunding the card. Then add an offline gift for the same amount. The steps to do this are:
  1. Locate the transaction in the Transactions Tab
  2. Select Refund
  3. Type in the portion of the total amount that you want to be a donation
  4. Select "No, the participant has already been reimbursed or will be reimbursed offline. Just record the refund in the Convio database." This will keep the money in the system, not refund it back to the card, and keep the totals the same for the event
  5. Now go to the user's profile in the Teamraiser Event
  6. Select "Enter Offline Gift"
  7. Enter the amount you just refunded and select cash
  8. This will create a donation that will now show up under the user's transaction tab, and can be soft credited normally