Raw Materials to WIP

Hello, we testing off of IFS App 10 and will soon convert to IFS Cloud. In our current old ERP system we issue materials from the warehouse to the production area and its immediately assigned to cost of goods sold (no visibility of WIP). Our inventory is averaged weighted cost and our system allows inventory to go negative. In order to prevent disruption when transitioning from our old system to IFS, we are looking at options to be able to issue material from raw materials directly into a WIP GL account and somehow be able to receive/close out shop orders/DOP orders through backflushing without getting errors for having insufficient materials. Our current idea was to create an inventory location with non-nettable so its not seen by MRP/purchasing and then have shop orders consume strictly from those particular locations, however we run into the insufficient material problem. The assumption I have seen with IFS is that it assumes your BOM is 100% accurate when backflushing which is never the case, how can we easily get DOP orders/shop orders in the hundreds/thousands to receive in without these errors of insufficient materials? Going into each shop order/DOP order to provide alternate part is definitely not an option, neither is having to manually adjust inventory on hand to push through the orders, and we cant get the inventory to go negative because we are using weighted average costing.