Can you extend a stay on rented points?

[EPCOT-O.G.]

I see there's a room available for one night in the middle of our three night stay. We're currently at Dolphin for our third night. Is there a way to book and reserve that room, and then contact WDW to extend the stay one more day via cash payment?

 

[BillPA]

You can't do anything with rented points, only the owner can.

 

[Tigger's ally]

If they are selling rooms for cash you can buy an extra night with cash and tack it on, but no guarantee you are in the same room.

 

[sndral]

I see there's a room available for one night in the middle of our three night stay. We're currently at Dolphin for our third night. Is there a way to book and reserve that room, and then contact WDW to extend the stay one more day via cash payment?

I’m confused about your question - I think you are saying that you have a 3 night stay booked as: day 1 DVC, day 2 DVC, day 3 Dolphin.
You see that day 2 DVC is available - which you already have? If your goal is to stay in your DVC resort & not move to the Dolphin on day 3 you’ll need to find an opening at your DVC resort on day 3 either through DVC or through a cash booking. If the room you want for day 3 is booked it can’t be made available by paying money for another night that happens to be open.
If you are asking something else - like extending your 3 night stay to a 4 night stay, then I’m really confused

 

[Sandisw]

You can book your own reservation that surrounds the reservation that you rented.

You can not modify or add to it. If you book the same room type and resort, you can certainly have WDW note you have the DVC reservation, but no guarantee you won’t need to be move rooms.

You could also ask the owner to send an email to DVC noting your cash stay. Depending on your contract with them, they may or may not do it.

But, no one will discuss the DVC reservation with you because it belongs to the owner and only that person can talk to DVC.