This page explains how to create a virtual room type with multiple rooms from a number of individual rooms.
'''Example''': You have a number of individual rooms updated connected to individual listings at a channel like Airbnb. You also want to sell them on Booking.com or other channel that requires a "room type" with a quantity of the available rooms. (this example will work with any number between 2 and 12 individual rooms)
It is assumed you already have setup the individual rooms each with a quantity of one, if not, create these first.