When you duplicate a task, there should be an option that allows you to choose a new due date for the duplicate and update the due dates of all subtasks relative to that new due date. So if my original task is due March 30th and it has a subtask due March 27th, I should be able to duplicate it, select a new overall due date of April 30th, and then the subtask will automatically receive a due date of April 27th.
This would really help my team. We use tasks and subtasks to track routine workflows that repeat every three weeks, and manually entering in new due dates for fifteen subtasks is a pain, especially when they should always have the same due date relative to the overall task due date.
