This is exactly what we did for our upcoming trip in early Sept. We went through a DVC points agent. Then once the reservation was secured and confirmed we had the option to add a dining plan. It can be ordered up to about 30 days before (i wouldnt cut it that close myself) but at that time you would have to pay for it in full. It does not need to be ordered at the time of securing your lodging. Also we were able to buy tickets from an authorized ticket seller (have used them several times now) and it saved us a little bit then from buying from disney direct. With the dining plan the agent contacted the owner and they booked it and we got confirmation within a few days. As for the tickets we bought them well in advance of the 60 day fast pass window and we able to add them to the my disney exp app so it made booking fast passes super easy. The dining plan will not show up on the disney exp app - it has to be linked once you get onsite to your resort. Hope this helps.