Complex sentence: While still continuing her work as a costumer, Vance began her work as film producer she joined forces with Alan Mruvka to co-found Ministry of Film as a Beverly Hills-based motion picture and television production company, which created and produced numerous films and television shows.
Split into simpler sentences: While still continuing her work as a costumer, Vance began her work as film producer. She also joined forces with Alan Mruvka to co-found Ministry of Film (MOF) as a Beverly Hills-based motion picture and television production company, which created and produced numerous films and television shows.