SRM - R3 item position mapping

Hi all experts,

the question is quite tricky; basically I have a report that, given a Purchase Order Number, must get the PO from SRM AND from the backend and do a comparison at item granularity.

From the SRM side, the task is quite simple; I can use the BBP_PD_PO_GETDETAIL FM to retrieve all the data I need about the PO.

The problem is: how to get a mapping (R3 <---> SRM) for every single item position ?

Thanks in advance 😉