We have no policy against it, as we can't verify that any supposed individual's postings are not the result of a group effort of bored teenagers in Siberia. I think it's slightly dysfunctional, myself, as I have a strong bias in favor of distinct independence in relationships. I'm interested in hearing as to why anybody would do that sort of thing, though.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.