The Cox Family never gained widespread popularity, but I think they were fairly well known among other musicians. Alison Krauss in particular championed them, producing some of their albums and doing a collaboration with them. They weren't much for song writing, mostly interpreted bluegrass and country standards. The band was a father and 3 adult children. I think all of them sang lead vocals some, although it was primarily 2 of the kids taking turns. They have many lovely songs, hard to pick one.
(I'm wracking my brain trying to think of another song thread to start and coming up with NOTHING; anybody else got something to help us pass the time?)