AP Import - Stop Overwriting Existing AP Data in PO Journals

When we use the AP Import feature and match AP Invoices to POs, the system looks at PO TOTALS, even if the line has already been posted on another AP Invoice. If you know that the balance remaining will match, you can select to post the Invoice anyway against the PO. This will cause ALL lines on the PO to show this Invoice attached - even lines that were already flagged with another invoice. It would be nice if either the system would not overwrite data here, OR even better, only look at lines that have NOT been posted to AP.