A friend of mine is involved in a relationship with a married couple. She and the male part of the couple - we'll call him "Joe" are involved romantically and his wife - we'll cal her "Jane" is aware and fine with it. She and "Jane" are good friends and both of them spend time together apart from "Joe" as well as with him. They all spend time together as well and function as a family unit.
This has been going on for a year and "Joe's" side of the family is aware of it and accepting of it. "Jane's" side of the family for the most part is OK with it. She has no living parents, and her extended family are accepting of it as well. "Joe" and "Jane" are wanting to have kids at some point and my friend wants to help take care of them and the relationship to go further.
My friend is wanting to tell her own family about it, but is nervous about doing so. Her parents are baby boomers who really only know the "conventional" family unit. They aren't strongly religious but come from a small town and have not really been exposed to different relationship styles. Her mother is mild mannered, and she is hopeful that she will be accepting. She is not sure about what her Dad will think and suspects that some members of the extended family (who are more religious) might be strongly opposed.
What would be the best way to break something like this to her immediate family? "Joe" and "Jane" have suggested having them watch a show like "sister wives" and gauging their reaction from that before proceeding further.