Split orders by warehouse

Enable MSI source selection when the resulting Magento orders should follow warehouse ownership. Each item's full requested quantity must resolve to one source.

This is not Magento's source deduction or shipment creation. Order Split records the selected source in its relationship data and comments; the normal inventory and shipment processes continue after order placement.

Choose a source-missing fallback that matches operations. Vendor-only grouping is useful when another system can route the order later. Blocking is safer when the selected warehouse is required before fulfilment can begin.