To add an additional room to an existing MSC Cruises booking, 1-866-829-1280 you must book a separate new stateroom and call customer service at 1-866-829-1280 (US) or your travel agent to link the reservations together. You cannot attach a new room to an active booking number directly on the website. To add a second room to an existing MSC Cruise reservation, you must call MSC customer service directly at 1-866-829-1280 (in the US) or contact your travel agent. Reserve a separate stateroom online or via phone 1-866-829-1280 based on current pricing and availability. Call MSC Cruises at 1-866-829-1280 (US) or +44-204-586-5316 (UK), or reach out to your travel advisor.