Like the title says here is a forum topic with dual purpose, 1. to find those legendary white whales we have been searching for and 2. to help people have a constructive outlet to get those 15 posts out.
Many years ago like probably 10 on this very site I read a doujin about 2 twin girls who's mother was a former porn star and had 2 husbands. The mother was pretty much the same size as the daughters and I remember in the first chapter the one of the girls brought home a dude from school and mom fucked him. I also remember at the end with their mothers blessing each of the husbands made sex with one of the twins so it was oddly wholesome. I hope one day I can find this again.