This article is from the Polyamory FAQ, by email@example.com (H. Wilper) with numerous contributions by others.
Good question. Ask it; there are many many approaches among the
people on the newsgroup. From cohousing to communal living to
group marriage to things-undreamed, there are a multitude of
ways. Design a new one and see how it works. Unlearn assumptions
about an old arrangement. Ask questions, and practice empathy.
Most of all, polyamory seems to be about building new
configurations of relationships rather than trading people in and
out like baseball cards. As amanda r. clark says:
"Poly is being open to the opportunity if it comes along, not
refusing commitments because something better might come
loping down the path."