Adding a continent after start of DONE3 fare question
 

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.

Yes, but the 10% discount complicates things. Depending on how the calculate the upcharge to add a continent you may lose the discount and face a high cost? The discount isn't part of the fare.

The discount certainly complicates things. To make it simple, oneworld have simply reduced their base prices by 10% - presumably the base prices will go up by 11% on April 12th.

Such changes require the original fare be used as a credit to the new fare, any difference is payable.

So methinks that if such a change is done before Apr12 then you will get the 'discounted' fare, after that the 'normal' fare.

I believe you would be able to add the continent at the sale fare rate. The rules of the fare is governed by what was in place at the time of purchase. In the past I have added a continent after starting travel and then a price increase. Same thing with surface segments and the 16 / 20 segment rule. Sometimes you have to remind them . I always print out the rules with the original ticket along with extra continents fares at the time of purchase.