I know you can get the DDP through
DVC even if you rent points right?
yes. never "free dining" but you can pay for it.
I know the member has to add that to your reservation. What I need to know is if they have to add that when you make your initial reservation, or can it be added later?
it needs to be added within 48 hrs of check-in. (you don't pay for it till you check in, though.)
but it's much simpler to make the decision when you make the initial reservation rather than repeatedly changing your rental.
Would that also mean that you have to get you park passes through DVC?
DVCers don't have to buy the DDP as part of a package. DVC doesn't sell tickets, so you're on your own for park passes...undercover tourist and maple leaf tickets are 2 respected outside vendors.