how to interface drop ship PO additional DFF details to SO additional DFF

We need to interface drop ship purchase order DFF details to sale order additional DFF either at header or line level.

As per standard process as soon as drop ship PO is received in system Sales Order Issue transaction is triggered for the drop ship SO, so we need to know how can we interface drop ship PO additional DFF to sales order DFF thtrough drop ship PO receiving and standard automated drop ship sales order issue.