ODOO 11 Old cusom mod modification -- 2

We have a mod for bulk confirming our Sales Orders and Delivery slip, which had been edited and modified by a few freelancers and created a few extend mods. Our system is using FIFO strategy, but somehow we find that the accounting is using 0 cost as journal entry as the first entry of FIFO while using the bulk confirmation button, we need to fix that to our first PO cost. Can provide test environment key and system for SSH and ftp download our mods