I had to do this for our June trip and it wasn't too bad. It would have been worse if we couldn't go at all. We were suppose to go in early June, but now we are going later in June through the 4th of July. It will be busier and hotter, but at least we are going. I did all my ADRs for the new trip first and then they went through and deleted all my old ones. One suggestion: If you don't get someone fast when you make the new ones, call back. It only took me about 15 minute total to make all the new ones, plus cancel the old ones.