How to determine the source sub inventory of a Backordered Sales Orde Line

We have a business use case to determine the sub inventory from which the item were picked during pick confirm and perform subinventory transfer to move the lines from staging to the source for backorder sales order line.

Once the lines are backordered form ship confirmation page we donot have an area to refer the source subinventory in oracle cloud.

Pls provide your thoughts .