Hello,

We sell equipment that we track the unique serial numbers on using Sales Orders.

We can charge the customers an advanced payment, then the balance on delivery.

We cannot figure out a way to do this in Books/Inventory:

- Cannot part invoice a SO with serial number tracking

- Cannot issue Retainer invoices as we cannot apply VAT correctly to them

- Cannot issue a separate invoice and book to the balance sheet as there seems to be no way to then credit future invoices 

Is there a solution to this? It is a big cash flow issues if we cannot do this.