Well, I'll take a stab at answering your question.
From what I've heard, it is not possible to add non-expiration at the
Disney store. When you purchase the tix, they inform you to add non-expiry at the parks or resort upon your arrival.
You can, therefore, add the option at WDW parks and resorts. You can add at any time during your stay, as long as you are within the 14 day window bedore they automatically expire.
The only "catch" is that if you add the non-expiry option, you will be charged for the origional number of days on your ticket, not the remaining days. i.e., if you buy a 10 dat MYW ticket, and after you use seven days, you decide to make the last three days non-expiring, you will have to pay the $$$ for the ten day non-expiry option.
Hope I explained this alright!
