Produmex WMS LInking Between DLN1 and PMX_DLPL

I am looking for a way to link back to PMX_PLHE Table I have seen the table PMX-DLPL which when the SO gets shipped and the delivery note gets created the details of the delivery note line are written back to this file Using this I can then link to the PMX_PLLI table and then in turn back to the PMX_PLHE table which is where the information I require is held. My question is what criteria do I use to link the DLN1 to PMX_DLPL tables This is difficult as there are multiple entries for each table.

Kind Regards

Chris