Ability to have a condition that supports "Modified by" is/is not one of a "Contact List field"

Peter F.

Need the ability to create a condition such that it operates when "modified by" field is not another contact list field e.g. "Requester."

This would allow me to setup an alert to notify users (e.g. Assigned To) when a change to a sheet is made but exclude them from notifications for the changes they make themselves.

We need this desperately.

Thank You