we have a situation where a vendor is requiring a series of partial payments against a Purchase Order we sent them. These partial payments are based on a percentage of the bill, not any specific quantity of line items on the PO.

For instance, we issued a PO with 4 line items totalling about $20,000. We paid 10% ($2,000) to start, and then another 50% ($10,000), and then the remainder of $8,000 when the items were received.

How do we enter the three different payments made such that the PO and its related items are associated with the total transaction?