Subcontract stock in MRP calculation

We have S/4 HANA 1610 but we are not using live MRP. We have scheduled background job to execute ABAP program RMMRP000 to run the MRP every night.

Our Scenario:

Total unrestricted stock for X material at Plant level= 13

MRP Type = PD (System is Creating Purchase Requisition if total available stock is less than Safety Stock, in our case it is 15)

Stock provided to Subcontractor (Vendor) = 11

In MD04 it is showing Total plant stock =24 (13+11=24)

When MRP is executing it is not considering this material and not creating Purchase Requisition, because system is considering Total available stock as 24 which is not less than Safety Stock, therefore system is not creating Purchase Requisition.

Expectation: We do not want the system to include Subcontract stock as available stock. We are expecting that MRP should consider this material and create purchase Requisition since available stock is 13 and which is less than safety stock qty 15.