If your goal is to merge them to get the 5th night free - this has been the case for a long time since dynamic pricing was put in place. Every touch of the reservation would generate a re-price with the current point requirement.

That said, for 4 night and shorter award reservations I always book them as individual nights - as it allows for repricing when only one night goes down (and the rest go up). I only had to move rooms when suite upgrades were issued for the individual reservations. Otherwise, it is rare to be asked to move rooms (as award reservation will be to the basic room anyway).

You can contact the hotel directly to let them know as well.