Advance progress payment

Hello,

We have a requirement, for specific items managed by client supplier wants 50% advance payment and remaining amount based on payment terms.  Since we can use advance payment options however we need to do manually adjust the prepayment during payment activity.  Else use complex PO use recoup.  Due to our business process we cant use complex PO.

Is there is way can we achieve the functionality?  is payment process can consider prepayment?

regards

madhu