Depends on who you book through. Only the DVC member can book the dining plan for you through DVC member services. I believe David's DVC rentals offers this option but I'm not sure about his competitors (I think the timeshare store does not). A private rental would be up to that individual DVC owner. Keep in mind that unlike Disney direct whenever a member books this (even if it is several months in advance) it must be paid in full immediately so they will (likely) require prepayment from you when they book it. Not sure if David's lets you add it after the fact or if you must book it when you make your reservation.
Also keep in mind DVC rentals through brokers are not able to be changed/cancelled after they are made (private rentals would depend on the owner and their rental contract) so I'd consider
trip insurance.