I propose that family be defined by written contracts created by the people involved, not by the government's decree that a family is two opposite sex married parents and their children, end of story. I'm not sure about this one because I have not met many people who consider themselves swingers, but as far as I can tell, most people who embrace the label 'swinging' support the idea that marriage or primary partnership does not need to be sexually monogamous and that having sex in groups of three or more is a fun social activity. Many swingers participate in swinging as couples. But many people think that swinging and polyamory are very different. Well, as far as I can tell, there is a difference of emphasis rather than anything else.
Swingers tend to focus more on the sex aspects than the romantic love aspects.
So the reality itself may not be so different. Sometimes polyamorists will downplay the sex aspects of their relationships and sometimes swingers will downplay the love aspects. One of my lovers expresses affection best through sexual intercourse. We already know that romantic love relationships usually include some desire for physical closeness and often it is difficult to draw a line between what's sex and what's non-sexual physical affection. Many people who do polyamory believe want to develop several long-term relationships that touch many parts of their lives.