Kourtney

About
Kourtney Mary Kardashian is an American media personality, socialite, businesswoman, model, and author. Kourtney is also Kylie Jenner's stepsister. In 2007, she and her family began starring in the reality television series Keeping Up with the Kardashians. Kourtney is the founder of a lifestyle brand called Poosh. Before this she worked with her sisters to run their boutique DASH & other ventures like Kardashian Kids & Kardashian Beauty.

Relationship with Kylie
Kourtney & Kylie seem to get along well and did a makeup collaboration for Kylie Cosmetics. However on an episode of Keeping Up With The Kardashians, Kourtney revealed that she thought no one told Kylie anything cause she 's Kylie Billionare Jenner.

Kylie Cosmetics
Kourtney has collaborated with Kylie 's makeup brand Kylie Cosmetics to release a Kourt X Kylie makeup collection.