It has happened to me. We booked our last vacation before the
free dining came out and then once it came out we called and asked if we could switch it, the CM on the phone told me if we did do this we will loose all of our ADRs because it will be a new reservation number (had all of my ADRs connected to our previous Reservation #), it really didn't bother me because I was able to get all of my previous ADRs for as close to my original times, if not better times.