Ability to mass update deliverable timeline start and due dates by a set number of days or business days.

When managing detailed deliverable timeline in real time to reflect delays to projects, it would be great to be able to mass update all start dates and due dates to be a certain number of days or business days before or after the dates that are currently set.

It is extremely tedious to have to go in and update all start dates and due dates manually to reflect this since this functionality does not currently exist.