I have a small story in the works and I need assistance.
I want Grandfather Higurashi and Totsai to be related but I am not sure which way. Either brothers, cousins, or in-laws.

I want Sango and Kohaku to be Totsai's grandchildren
and of course Kagome and Souta are Higurashi. But which family would Shippo fit into?

Sesshoumaru is older than Inuyasha and Rin. I want Rin to be the middle child but just how far is the age gap? I am thinking Inuyasha is no older than 8.

Sesshoumaru, Kagome and Sango are about the same, high school age, not sure which grade yet.

How much older is Kohaku to Souta?

Note: all are human

Thanks to any that help.

I think Gramps and Totosai fit more as in-laws because in-laws are ‘supposed’ to argue and they seem the type to want to argue a lot over everything.

Shippo, I think is more of the Sango/Kohaku family because then Shippo can adore Kagome. He can either have a childish crush on her, a sister bond with her, or she can adopt a motherly bond. It just gives you more room to work.

If Inuyasha is going to be eight then I think Rin should be about ten or eleven and then Sesshoumaru, Kagome, and Sango somewhere between the ages of 16-18. Personally, Sesshoumaru seems much older therefore he should be eighteen and Kagome/Sango seventeen.

Kohaku always seems about twelve or thirteen and Souta somewhere around ten or eleven with Rin. This way all the middle children are in Middle School, Shippo and Inuyasha (both around eight) are in Elementary, and then all the older siblings are in High School.

Well, that’s my opinion

I hope it helps! Happy writing!!!

I like the in-law fights idea. Now the question is how are they in-lawed? Time to do a family tree I think.

They could be related via their son's, Kagome's and Sango's fathers. If you kill off the fathers then the mothers can find friendship with one another, causing them, to hang out alot, which would be a good way for the two families to be close.