If you have a room only reservation.. ANY reservation, but even with AAA rates.. You can go to an AAA TA and have them 'Take Over' your reservation.
You must sign a permission form, and the AAA TA can take your reservation and turn it into any kind of package you want.
If the first TA can't do it.. go to a different AAA because they must not be well informed! Make sure they have a certificate from the Disney College of Knowledge or whatever it's called.
I had AAA room only ressies I made myself over the phone with Disney. I decided (just last week, and i leave in 2 weeks!) to change to a package with dining. I had a split ressie so this made it more difficult with the tickets and such.. but anyway..
I called WDW and they said to do the takeover thing with AAA cause only they can keep my room rates the same. Went to one AAA.. and she said she couldn't do it. I went to another, and she said she'd check.. she checked, and said no, but I can rebook your one ressies with the package, but they's no availability for the other resort. I took it. At least one part of my trip would have the dining plan.
Well I was confused because it's not what WDW told me so I called back to be sure. I was transferred a bit, but got to someone who was very nice and seemed very knowledeable.. she said find another agent.. it is easily do-able.
So I did.. my 3rd agent... she knew EXACTLY what I was talking about. It's NOT rebooking.. they take your original ressie, you sign a paper, and 24 hours later they have you booked with the same ressie in a package. You don't need to worry about getting a room, or if the AAA rates will be available for that room You already have the room and the rates.. she just adds the rest. And an AAA TA is the only one who can do it.
BTW.. she was the only one of the 3 with the Disney College of Knoweledge certificate.. it was showing proudly on her desk, and on the desk of the other 4 agents there too.