Personally I haven't done it, but, according to what I've read here, you need to pull up your existing ressie and then pull up a new window with all the Ding information. I guess you cancel your original ressie in the first window and then IMMEDIATELY make the new Ding ressie. You must cancel the first ressie in order to have the Ticketless Travel funds available for your Ding fare. I have $59 fares booked for early June, so, if a Ding comes up for my dates at less than $59 I may try it, but, I have to admit I'm a little apprehensive about it.