You also need to go through the owner for any changes to the reservation. A non-owner cannot change the names on the reservation, add a view request, buy the dining plan, book DME, modify dates, etc.
Rentals also tend to be VERY restrictive in ability to cancel or make changes. That's a big part of the trade-off for the savings involved in a rental. Members renting their points are just people looking to cover their cost while getting someone else a great deal. They don't have the resources of Disney Reservations which allows cancellations up to a week before arrival (or whatever that policy may be.)
I was recently reading comments from someone who had rented points for a visit that was still 7-8 months away, and then found out she was pregnant with a due date just before the trip. She was angry / dumbfounded that the owner wouldn't make any accommodations.
To be painfully blunt, that's the deal you make when renting points. Part of the reason you're getting that room for 50-60% off Disney prices is because of the irrevocable commitment. If you have any concerns about being able to make the trip due to injury, illness, etc., BUY TRAVEL INSURANCE IMMEDIATELY...or don't rent in the first place.
Good luck.