Tiefling

Found it!! Thanks Drpaladin!!!

Either Incest, Young friends, or Rural, but I’ve searched all three with keywords, but the title would help

I read a story years ago about a kid who gets a new adoptive brother, they have lots of sisters, and their house has secret passages (kinda?) It also has a fair deal of chapters, I know this isn’t allot to go on but if anyone’s read anything like it I’d love to try and find it again