My original idea had been to use a look up custom field to link back to the physical item and then provide a custom route that would do the replacing with the physical item and then call the real Jiwa post order route.
I now realise I may not need the new route as I can use the start deserialise event to edit the DTO's data instead are the only fields I will need to change in JiwaFinancials.Jiwa.JiwaServiceModel.SalesOrders.SalesOrderLine:
- Inventory Id
- Part No
- Non Inventory
- Aux2