Responses
last chapters of http://www.mangago.zone/read-manga/kareshi_glamorous/
I think this is similar to what you described but the semes are not brothers
http://www.mangago.zone/read-manga/oz_no_matenrou/
omg thank you thats been bothering me so much ahahaha :3
I've been searching for ages and I just can't find it!! It's a yaoi manga about two brothers (no incestuous) in separate relationships, both brothers are semes and theres a scene where they make their ukes kiss?? I think there is also a bit where the older brother gets spied on doing the do in the living room??