 Sibyl's father Silas Sanderson was a California politician and lawyer; after serving as Chief Justice of the Supreme Court of California, he became a highly paid legal advisor to the Southern Pacific Railroad.After his death in 1886, she and her mother and sisters moved back to Paris and became transplanted socialites.Sanderson proved to be a remarkably gifted singer and began to appear on the stages of the Opéra-Comique, and later Opéra, in Paris, most notably in the works of Jules Massenet.