Complex sentence: The Aberbach brothers established their cousin, Freddy Bienstock, as head of Elvis Presley Music-in effect, a subsidiary of Hill & Range-and organised writers (including Leiber and Stoller) to provide songs for Presley's films and albums.
Split into simpler sentences: The Aberbach brothers established their cousin, Freddy Bienstock, as head of Elvis Presley Music-in effect, a subsidiary of Hill & Range. It also employed writers (including Leiber and Stoller) to provide songs for Presley's films and albums.