I have some invoices I've raised for a company that has a policy of paying the invoice in two payments. One payment is the non-GST component, the second payment which comes a month later is the GST payment. For example, my invoice is $100+GST = $110. They pay me $100 which is the non-GST payment and then a month later they pay me $10 for the GST component. The RECEIVE PAYMENT window doesn't allow this type of allocation. How can I process the payment correctly?