Booking Manager gives you the possibility to create an invoice for additional items payable in base.
Invoices are very easy and simple to make in few clicks.
When you have extras payable in base on your reservation (1.)
and you want to issue the invoice for them go to Invoices tab (1.) and press New (2.)
This in effect opens a new reservation with custom status for the same boat and client with all options taken from the calculation of the original reservation and invoiced (check on Options not invoiced is not applied) (1.) and the total price of the items being invoiced (2.). Additional items can be added (3)., just like on the parent reservation.
Next, click on Invoice detail (1.) and on Create invoice (2.) button.
Close the window and you will find the invoice on Invoices tab (1.) of the parent reservation where you can click on it to select it (2.) and Print (3.) it.
Result is the regular Booking Manager invoice for you extras payable in base