You probably can book online then call Disney and have the plan modified. I did this last year when they ran a promo. I called and gave them the code for the new promo and they modified my package.
Thanks, I was kinda just looking for a quoted price, not booking yet. We're going 2/14-2/21 and I was all ready to book the package with the free hopper/waterpark & more upgrade, then I got this code in the mail today for room only. Decisions, decisions... ~~