@Courtney22 You put up 2 listings, one for one bedroom and 2 guests (or however many the room is suitable for) and another listing which is for both bedrooms and listed for 4.
Then you link the calendars so if one listing gets booked, the other becomes unavailable for those dates.
On the one bedroom listing you only have photos of that one bedroom and the bathroom and shared common spaces, on the other, you picture both bedrooms.