Kylie Jenner: Rob Kardashian's My Bro ... Blac Chyna or Not (VIDEO)

Rob Kardashian has clearly found his way back into the good graces of his family, despite the initial war that broke out after he started dating Blac Chyna.

Kylie Jenner -- who's been hooked up with Chyna's baby daddy, Tyga, for well over a year -- took a field trip with her big bro Tuesday to Diamond Supply Co., a streetwear brand, in the San Fernando Valley.

They clowned around and hung out with Nicky Diamonds ... a big deal since we haven't seen Rob with any of his sisters since Khloe threw him and Chyna out of her house.

Blood ... sometimes thicker than water.