Non Labor Billing Extension

Hi,

Does anyone have any suggestions for determining the invoicing currency at the point in time that the non-labor billing extension is called?  Before the generate draft revenue process is run the invproc_currency_code on pa_expenditure_items_all is null.  I would prefer not to try to look at the invoice currency on the customer form as there could be multiple customers setup for the project (using customer at top task functionality or possibly bill split functionality).

Suggestions?

Thanks,

Paige