Need to interface intercompany AP invoice lines to Projects

Standard functionality is that for intercompany AP invoices (i.e. source Oracle Projects Intercompany Invoices) that originated in PA, following the PA-AR-AP route, the AP invoice does not interface back to Projects although the project fields are populated.

For tax related purposes, we need to update the IC AP invoice in the AP interface before running Payables import - creating an additional 'item' line - which DOES need to interface to Projects as an expenditure.

Is there a way this can be accomplished? I have tried playing with the PA_addition_flag in the AP_INVOICE_LINES_INTERFACE table but have been unsuccessful in interfacing to PA.