Keep in mind that for the
FREE dining plan there are a limited number of rooms available that can have free dining. If you already have a room only reservation it can't be converted to a free dining......call AAA and ask them if they have any FREE dining plans available. If they don't have any left, you can call Disney directly and see if THEY have any left.
I know it sounds odd to say that AAA may be sold out of the free dining, but Disney may still have some available....but picture the analogy with physical tickets.....for instance there are 1,000 free dining plans available.....AAA has 400 tickets of them and Disney keeps 600....when AAA sells it's 400th plan they're gone....but Disney may still have some in it's pocket.
Using the same analogy.....Disney may have 1,000 rooms, but only 600 of them are eligible for free dining. So while Disney may not be sold out on rooms, they may not have any free dining left. Now, those 400 rooms that didn't have free dining available can still PAY for dining plan of course.
I hope that makes sense...
Also...if you want in on the free dining, you better jump on very soon....I've read that Disney is completely sold out on the value rooms with free dining. Not sure if AAA.