How to enforce every item requires a primary supplier association?

Summary

How to enforce every item requires a primary supplier association?

Content

Looking for a solution to make certain all items assigned to a specific organization have a supplier association defined which is marked as primary.

Creation of an item without primary supplier association should be blocked, as well unchecking the primary flag without making another supplier association as primary for any specific item. Adding an additional non-primary supplier association or switching primary association should be allowed (as the end result remains with a primary supplier association)

Version

r13 u18c