Sienna was a female individual who was the daughter of Mirienna and Ostar, who lived in a village on the planet Zeffo. The Empire occupied Zeffo, and Sienna's father Ostar distracted stormtroopers so that Mirienna and her daughter could escape and was killed in the process. After his death, Mirienna sent Sienna to meet with her grandfather on Chandrila while she joined Saw Gerrera's Partisans but decides to leave Mari Kosan's cell to raise her daughter after learning her husbands death.