Lost a story - can't remember title or category

[mabsls]

Family goes to a camp. The cabin has three rooms. The kids are in one room, the parents are inthe middle room, and another couple is in the third room. One of the kids notice the mirror is a two way mirror and watches some swinging going on. They compare notes with other kids. Eventually everyone gets involved. Swinging family summer camp, but what's the real title and what category is it in?

 

[driphoney]

Family goes to a camp. The cabin has three rooms. The kids are in one room, the parents are inthe middle room, and another couple is in the third room. One of the kids notice the mirror is a two way mirror and watches some swinging going on. They compare notes with other kids. Eventually everyone gets involved. Swinging family summer camp, but what's the real title and what category is it in?

Incest?

 

[mabsls]

I can't remember if the story is in incest or novella - I've tried paged through categories and I've tried searching, but I haven't found the story so far.