I have the same question as to how to do this. I added an empty lot 50x50 in size set it community visitors allowed and tried add "The Erutuf Future Lounge" to the empty lot, but I can't see my empty lot and it doesn't add the Lounge as far as I can tell.
Would someone be able to help me with this?
Btw I am trying to add more community lots to Moonlight Falls at this point.