Who is Mata Kingsolver from Citizen of the Galaxy and what is their importance?

Mata Kingsolver is Jeri's sister. She serves the Sisu as the Junior Firecontrolman until she is promoted to her brother's position. Mata and Thorby begin a romantic relationship, which is quickly ended by Grandmother trading Mata to El Lido. The Free Traders do not allow marriage between family members, even if there is no blood relation. Grandmother is not going to allow her family to be the subject of scandal.