Complex sentence: Butterfield and Swire (B&S), who were the Far Eastern trading company of JS&S, were appointed from the formation of CNCo as Eastern Managers, all correspondence with JS&S, the London Managers, being conducted by the offices in Hong Kong and Shanghai.
Split into simpler sentences: Butterfield and Swire (B&S), which was the Far Eastern trading company of JS&S, was appointed from the formation of CNCo as Eastern Managers. All correspondence with JS&S, the London Managers, was conducted by the offices in Hong Kong and Shanghai.