Matched In Summary - Link to PO Lines

Here's my issue:
We are matching in summary so when we post to GL, there's no way to work our way back from a GL transaction to see which PO Lines were combined to make up that transaction.

Has anyone been able to find a link through all the various tables (GLTRANS, MAINVDTL, APDISTRIB, etc...) to be able to create a report?