Originally Posted by Calchas

1. If you make no changes to the first flight coupon (the first flight), you pay the delta in any taxes, airport fees and airline surcharges, plus any increase in the fare. If you are changing the ticketed points or the first flight coupon, then in addition to that you pay the 125 USD fee.

2. After the first coupon is used, you can change the ticket within the original rules for 125 USD fee plus the delta in any taxes, airport fees and airline surcharges.

The relevant rules are---