Our family is not aware of our search for another wife, yet.
However, Bexy's brother is pagan and has a wife and "live-in-girlfriend" (for all intents and purposes, another bride). Bexy's mother accepts her only because it is the only way to see her son and her grandson. Bexy's sister basically ignores her. Gifts given are usually to "[brother] and [legally married wife]" and "[girlfriend]". So, any "couples" gifts are given to the actually, legally married couple--and [girlfriend] is given a 'token'.
Our family, however, have completely befriended them. We spend lots of time talking with them and to some degree "study" their relationship and the pitfalls they have faced. (Mind you, many of their pitfalls we will never face--like all the difficulties they have with an "open relationship".)
So, this season, we are considering inviting them over to spend Christmas Eve at our house instead of Grandma's and have a big celebration here. (Grandma has also become annoyed at how big our families have become. With six children for our family, three for Becky's sister and one--with one on the way--for her brother, Grandma is having difficulty dealing with the "chaos".)
It's a mixed bag for us.