I believe that I know the answer, but would appreciate a confirmation of the rules.

I buy a DONE3 during the 10% discount sale. Once I have flown on the first segment, I can add another continent at the prices in effect at the time of my original purchase for the country where one began the trip (South Korea, Poland, etc) plus the $125 reissue fee. Correct?

I realize that the exchange rates may be vastly different in the future, but locking in the low fares now is my intention. My gut feeling is that once the sale is over, the change in prices will be more than the 10% discount on offer at this time.