If you find a code Disney will apply that code, assuming it is better than the
AAA discount. Just call CRO and ask if they can apply the code since there are always a limited number of rooms available at any discount code. We did exactly this last year and went from a small AAA discount to a MUCH larger code discount.
Keep checking mousesaver.com for codes. I was very surprised in how much we saved!!!!!
Good Luck!!!!!
ps....they simply modify your reservation.....no need to cancel