If under my Disney experience you see modify res than you can do it, supposedly. I say that because when I tried and hit update it would not update mine and I had to call. The one thing I did do, was change the age of one of the children who turned 10 just before trip, that did not work well, it kept the old age and added the new age and still even after I called Disney I have two children with the same name going on vacation and two children pop up with different ages, so half the dining ressies have her as 9 and half have her as 10. I give up trying to fix it, and Disney could not help when I called them. So my advice, call if you can because it does not seem to notify very good.