Reserve only what can be allocated
Review available stock at the fulfilling warehouse. A partial reservation allows the order to progress while the remaining demand stays visible.
Separate physical work from order demand
Confirm a pick list for the quantities picked. Complete a packing slip for the quantities packed. These records describe completed warehouse work, not merely what a customer ordered.
Dispatch the shipment
Dispatch the quantities in the shipment and review the remaining order balance. Do not assume a dispatched shipment means the whole order is complete.
Follow the backorder
Review outstanding demand when replenishment arrives. Reserve and fulfill the remaining quantities using another shipment.