I do not believe that Disney will allow you to exchange one ticket for two. I think you're out of luck. If you purchased the tickets at a discount before the recent price increase, at least you're not loosing too much money. You probably paid what an 8 day ticket costs now, and that's only $40 more than a 4 day ticket. So, it's throwing some money away if you don't use all the days, but it's not too crazy.
Any ticket bought from a discounter or as part of a WDW Resort package or from the Disney Store should be used at least one time
to enter a Theme Park BEFORE doing any upgrade.
If that is done, Disney will "bridge" the price for that ticket up to the current
gate price for a new ticket of the same assets for the purpose of the upgrade.
It cannot HURT to use a ticket at least one time
to enter a Theme Park BEFORE doing any upgrade…
and it just might HELP, financially.
And every penny counts! So thanks, Robo, for that advice. I will definitely use our tix in 3 weeks once before upgrading. My first EPCOT cheers is for you!