Complex sentence: Murphy had worked with Seger previously in his very early years prior to his later notoriety, and has continued on with Seger on most all studio session work since 1973, in addition to all of his tours since 1978.
Split into simpler sentences: Murphy had worked with Seger previously in his very early years prior to his later notoriety. She has continued on with Seger on most all studio session work since 1973, in addition to all of his tours since 1978.