We have an item that is shared across multiple subsidiaries. It's already used by all of them. But going forward, we don't want a specific subsidiary to use it anymore. How can we prevent users from being able to select it? Is there a way to achieve it aside from using a script or a workflow? This is like inactivating the item for one subsidiary only.

@Luis Unselect that subsidiary from the item record?

There are transactions that already make use of the item in that subsidiary.

Worflow with action as error?