Read/Unread count should be consistent across users

We are using a shared task ID with 4 team members, and due to the nature of Our work it is not possible to create personal folders only, all team members need to have visibility and possible action out of different mailboxes (eg to index, to process, vendor correspondence, etc). Since each user's read/unread count is completely different it is nearly impossible to tell what requires action and what has been completed unless the document is moved to a different folder which again due to the nature of work is not doable since there might be follow-up actions related to that same note that all users need to view. 
I would highly welcome a feature where marking a doc as read/unread would be showing for all users who have access to the task ID so they have an accurate way to size up the workload.