By default when you place a customer order and item is out of stock the system will set the missing quantity against vendor order creation. As a result when customer order is processed related vendor order(s) will be created for missing items.
- Admin --> Site Settings --> Additional Settings
- Enable [ ] Default VPO QTY to 0 when placing CPO and click Save & Close
- Admin > Site Settings > Additional Settings
- Enable [ ] Disable Auto VPO for IK Components and click Save & Close