...
If the exchanged item is at a lower cost, a credit will be added to the participants profile. You can either refund the family the amount of the credit, or the credit can remain on the participants participant's profile to be applied to a future transaction.
If the exchanged item is at a higher cost, there will be an outstanding balance added to the participant’s profile. The family can log onto their My Account, and pay for the invoice from the payment menu, or send in the amount by an offline method of payment.
Why is are the exchange Items greyed grayed out?
There are a few reasons why an exchange can not be made to an invoice - there are credit card installments attached the to the invoice, or there was a refund made.
...