Answer: By default, DISCO automatically propagates a tag to the entire family when viewing a parent document. For example, if I am viewing a parent email and tag the email "hot" within the document viewer, the email's attachments (children) will also get tagged "hot". To propagate a tag UP from a child to it's parent, you must mass tag (see screenshot below). Read more about how to mass tag HERE.
*Please note, this information holds true for all matters created before 12/06/2016.