From Allears.net
UPGRADING WDW TICKETS
Last week, we became aware of an apparent unannounced change in Disney's policy regarding tickets that were purchased from non-Disney sources. Several guests reported that when they attempted to add a day to a Magic Your Way ticket purchased from a non-Disney source, they were refused and told that they would have to spend more than $100 for a single-day ticket. Several tried at both their resort concierge and at a guest relations window and were told the same thing.
We called the Disney Ticketing office and and spoke to a supervisor. We were told that commencing with last week's price increase "third-party tickets can no longer be upgraded to passes at a pro-rated rate, have days added, or have options added at a discount." A different call to a second Disney source confirmed this, but added that this does not affect AAA.
On the basis of all that, we changed our ticket FAQ to reflect what we believed to be the new policy. We expect that we will learn of policy refinements as time passes, and will keep watching the situation and listening to our readers' comments about any problems or successes they have had in this area. - March 3, 2014
Update March 5, 2014: This apparent policy change affects tickets bought from third-party sellers by guests who may be hoping to avoid an increase in gate ticket prices. The change requires you to pay the difference between the old ticket and the new ticket first, before any upgrade. We have no information yet on how Disney will separate those ticket purchases from ones that were made prior to the latest increase or how many previous price increases may be affected.
Heres a link to the entire page: http://allears.net/pl/ticket.htm#credpass