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