Open Purchase Order report....if received partially add "GoodReceipt Date"

Have a Open PO Report using : OPOR and POR1. If received partially then I need to add the field "GoodsReceipt Date" from table OPDN.

PO would be Base document and GR would be Target document. Whatever does not have a GR will be blank or null.

Not sure how to link OPDN to the existing report.

Help Please!!