During a full physical inventory, it would be helpful to lock/suspend inventory quantities during the process. Perhaps a "special Physcial Inventory function" that would lock the inventory quantities and cost values for a particular date/time to allow for bulk adjustments to qty and costs for regular physical inventories?

The special Physical Inventory Function would allow the inventory to be adjusted as of a fixed date/time in the past. After adjustments are complete the special function would integrate revised inventory data back into the inventory records as of the date of the special function. All inventory activity (sales/purchases) that happened after the "special physical function date) would still process adding or removing of the inventory based on the transactions that occurred therefore keeps the inventory data accurate. Contact me if you need more information to understand.