Making Supplier/Site Mandatory For Requisition.

Summary

Making Supplier/Site Mandatory For Requisition.

Content

Hi - We have a requirement to make supplier/Site mandatory while creating a requisition. This can be achieved via sandbox personalization on "Enter Requisition Lines" UI.  But, in our case, some requisition can be created manually and some via min-max. The sandbox customization working fine for manual requisition creation via "enter requisition line" UI. But how can we make supplier/site mandatory for min-max requisition? 

Note - Min-Max requisition will be created in INCOMPLETE status.
For some items, we have BPAs available, for such items when the requisition created via min-max, BPA gets stamped and we don't need any supplier in such a case.