According to Jain tradition:

• The sister of Bhagwan Mahavir is Sudarshana (also called Sudarshana Devi / Sudarshana Mata).
• She is the daughter of Raja Siddharth and Rani Trishala, so she is Mahavir’s elder sister.
• In Śvetāmbara narratives, her son Jamali is the one who later marries Mahavir’s daughter Priyadarshana and later causes the first schism in the Jain Sangh. ( jainknowledge.com)

You can read a bit more about Mahavir’s family here and about his family tree here .