Responses
I only know of this yaoi manga
http://www.mangago.me/read-manga/bokutachi_futari_ga_koisuru_riyuu/
its the story of every slutty sister /brother seducing their siblings' idiotic spouses that actually wants to be seduced.
Any romance manga where the protagonist's lover died and consequently he/she ended up with the dead lover's twin instead...
Thanks in advance...