configuring the number max of items for a single booking
I want to make the maximum number of items that do not control the inventory depend on the maximum number of items that control the inventory. For instance : the customer can book 1 to 9 vehicles with 2 adults min. and 4 adults max., and 0 to 4 children. These items do not control inventory, which is based on the number of vehicles. In the booking page, I want to limit the number of passengers to the capacity of the number of vehicles booked, with a max of 5 people on board of each vehicle. How is it possible ?