Complex sentence: His association with Sondheim began with the workshop of "Assassins", and after "Forum" he appeared with Victor Garber in the workshop of "Wise Guys" (later retitled "Road Show").
Split into simpler sentences: His association with Sondheim began with the workshop of "Assassins",. In 1999, he appeared with Victor Garber in the workshop of "Wise Guys" (later retitled "Road Show").