When you use the VA01 to create a new order, the sap system will get the delivery plant by the following logic.
Step 1.Check whether the item is Higher-level item, the system will use Hierarchy item's plant;
Step 2. Check whether the plant field value(RV45A-DWERK) was input manually;
Step 3. Check if a specification exists in a customer-material info record (KNMT-WERKS);
Step 4. Check if a specification exists in a specification exists in a retail (WRF3 table);
Step 5. Checks if a specification exists in a customer(Ship-to) master record(KNVV-VWERK);
Step 6. Checks if a specification exists in a material master record(Sale VIEW 1 MVKE-DWERK);