If you do not book them together you have painted yourself into a financial corner. The worse case is the crew who is determined to work all the angles on their own chasing a few dollars in savings. Then leaving the rest of the crew sitting at the dock the first night waiting in vain for them. Just because it worked for them last time or they read on the internet how it works brilliantly for others is no guarantee it will work for all in your crew on your next excursion. Do the math on what the total cost of the trip is for the entire boat. From there it my help everyone see what the losses and costs of the delay waiting for someone or a bag can be. Penny Wise, Pound Foolish comes to mind and/or friends do not let friends ride the ferry is another.