Invoices can be created from Invoice page (Finances > Invoices) or directly from reservations. In this case all the items from reservation will be added to the Invoice.
You can create offers or pre-invoices for your clients from Pre-invoices page. You can send preinvoice in PDF to client's email directly from Bentral.
If you receive advance payment for service which is not rendered yet, you can create Advance Invoice. Advance invoices can be created directly from reservation where you enter the amount you received and the system will create an Advance Invoice with partially paid amount.
In case of multiple advance payments you can create Advance Invoice for each payment.
When the service is rendered and completed you need to create final invoice where all the Advance Invoices are indicated as advance payments.