Um, are you asking about a poly group or a swinging group? I ask that because swingers refer to themselves as being in "the lifestyle," as I understand it (that's how the swingers 'round here refer to things).
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.