MR actually does not entitle a person to receive night credit for up to 3 rooms per stay. They are supposed to get night credit for only 1 room per stay. Of course sometimes persons have been able to get night credit on more than one room, but the rules state your not supposed to.

As for your main question, I have never received points for more than 3 rooms at one time. Not as FS Marriotts or CYs either. The way around this one is depending on the number of rooms (and 4 or 5 rooms may not be enough), is to call their Meetings & Events group and set up the rooms as an event. You may be able to get more points this way.