There's going to be some changes made to the DDP reservation system for DVC members.
For example, let's assume that you are staying 7 nights and your parents will be arriving for the last 3 nights. Let's say you want the dining plan for the first 4 nights, but not the last 3 when your parents will be with you. You can break up your reservation into two 'accommodations' where the first one has the dining plan and the other one doesn't. You will have the same reservation number and will not have to change rooms, but you will have two accommodations associated with it.
However, you won't be able to have the dining plan AND your parents do not have it simultaneously. You either have the dining plan or do not, for each accommodation that you make within the reservation. And every person on that accommodation will have the dining plan or will not have it.
I think I got that right. Others, please correct me if I am wrong.
This will be implemented this month. Check out the following thread for details.
There are some changes brewing but none of us know for sure how it's going to work out. Regardless, it looks like the DDP will still be require for all parties for the days in question if I recall the discussions correctly and as WildernessDad suggested. You could get separate rooms such as getting a 1 BR and lockoff studio.