HI @Judy36, you can create a third listing with the two rooms together plus whatever other spaces are included. Make sure to label the rooms to keep them straight, e.g. Blue Room, Red Room, and Two Lovely Rooms for example. Then you can sync your calendar so that you don't double book, i.e. if one of the two rooms is booked, the combined listing will be blocked on your calendar => theoretically! I'd want to really keep on top of this and definitely not use instant book, since you'd want to make sure you weren't double booking before replying in the affirmative.
But I think it is possible and probably worthwhile - as there are many fewer listings for say 3 or 4 than for 2, so when someone searches for a place for 3, your listing has a better chance of popping to the top than it would with a listing for 1 or 2 (at least this was the case in my area when I contemplated adding a 2-bed room to my studio listing - I now have two listings, one for the studio and another for the 1-bed which includes the studio for a total of 4 people). Hope that helps! Susie