Complex sentence: The ballet half was sold to Willam and Harold Christensen who became artistic director and appointed director of the San Francisco Ballet School, respectively, the San Francisco Ballet Guild was also formed during this time as a support organization for San Francisco Ballet.
Split into simpler sentences: The ballet half was sold to Willam and Harold Christensen, who became artistic director and appointed director of the San Francisco Ballet School, respectively. The San Francisco Ballet Guild was also formed during this time as a support organization for San Francisco Ballet.