Is Madaras Obito a grandchild?

Is Madaras Obito a grandchild?

They are Uchiha after all so they are related by blood to some extent. If you're asking if Madara could be his great-grandfather or something like that, it's not likely. You don't need to be a direct descendant of Madara to awaken a powerful Sharingan. Even if he was a descendant, the show never hinted at it.

Is shisui Uchiha obito brother?

Jay.

Who is Kakashi's brother?

Shinji Hatake Shinji Hatake is the older brother of Kakashi Hatake and a famous shinobi of Konohagakure, who has the title, the "Blue Fang of the Hidden Leaf", which makes him a bare resemblance to his father, Sakumo Hatake.