How to create a PO from Process Requisitions UI with a different procurement business unit

Summary:

We have configured Service provider relationship for two BU's in order to configure Centralized Procurement flow.  US BU will be Procurement BU and UK BU will be the requisitioning BU and the legal entities for both the BU's are different. Requisition is created from Requisition Line Entry with Ship to location belonging to UK BU. Source agreement and supplier details are not provided. Requisition is approved. It's visible in Process Requisitions UI only when the procurement BU is set as UK BU. The expectation is to create PO in US BU for this requisition.

This works if the supplier details and source agreement is provided in the Requisition.