In Oracle Inventory Fusion, can we create user supply or artificial supply?

Summary:

We have a need to an artificial supply or user supply which should be taken into consideration while running Min-Max planning. We have external systems where we maintain inventory and Oracle covers much of our Inventory and planning also takes places in Oracle.

We cannot use subinventories in Oracle to bring that onhand from external systems, as it may go on our books and it can become duplicate. Onhand in External system and onhand in Oracle. Creating open requisition lines or un-approved requsition lines is also ruled out, as Min-Max planning doesn't consider the open Req lines as supply.