Tasks and relative dates

With Capacities, I can use tasks that contain nested sub-tasks. If I have to reschedule my "master" task, It would be nice to have nested sub-tasks updated automatically. For exemple, if a task is postponed from Monday to Wednesday (two more days to complete it), it would be nice to have some of (but not necessary all) the sub-tasks rescheduled as well (either two days later … or two working days later)