Item quantity cannot be less than the total quantity used on existing inbound shipments.

AI generated answer (using internal Slack threads):

Based on the conversations, it appears that the quantity of a Purchase Order (PO) linked to an open inbound shipment can be adjusted, but not to a value lower than what is already linked to the inbound shipment. If the supplier over-ships and allows you to keep the extra, you can add overages on item receipts if you have the 'allow overages in item receipt' feature enabled. However, this might affect the average cost. If you receive more than the inbound shipment quantity, you might need to update the PO quantity instead. If you need to adjust the quantity to a value lower than what is in the inbound shipment, you might need to update the inbound shipment and possibly an ownership transfer first. If you need to close the inbound shipment lines and receive quantities beyond the inbound shipment quantity, you might need to receive the quantity in full and create an Inventory Adjustment for the quantity that should have been closed. If there's an overage, you might need to create a second PO/Inbound Shipment for the overage. Please note that these are workarounds and might not be the best practices. Always consider the impact on your average cost and other financial metrics before implementing these workarounds. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******