Dashboard Global Filter Associated Records with Relationship

It is our best practice to log certain Timeline Activities to the Company and Relate them to the Relationships.  I need to create a Global Dashboard filter based on an ID of the Relationship, however, I can only see a Company lookup.  The WHO/WHAT resolution that is available in data Designer and other places in Gainsight is not available in the Dashboard Global Filter configuration.  Please address this product gap so the Global filters will work as expected in this scenario.