guide if you are confused:
Rinzou + Wife = Shinji
Rinzou + Servant = Tamaki
Rinzou + Tamaki = Utsuro
Tamaki + Seiichi = Ayato
Shinji + Chika = Mishiro
Also worth mentioning:
Chika and Ryotaro are siblings
Ryotaro is the uncle of Mishiro
Utsuro is the friend and love interest of Yuzu
Ayato is the friend and cousin of Mishiro
youre welcome