How to force a different exchange rate in incentive compensation transactions?

Scenario: Plan is specified to pay commissions based on two events. Event 1 is defined when the order is processed and event 2 is defined as the payment collection from AR import process on the subsequent customer invoice.

Problem: Incentive exchange rates are based on the event date specified on the processed transaction. When the order is received it has an event date that determines the exchange rate that will be used for conversion purposes on subsequent customer payments coming from AR. The challenge is that the payment transaction has a different event date that will derive a different exchange rate. We are trying to insulate the sales rep from exchange rate gain/loss and essentially fixing the rate to the original rate used on the Order transaction. The obvious solution is to change the