Use additional levels of subtasks to organize your work in more granular detail. This allows you to capture all the necessary tasks that need to be completed for project success and completion.
You can nest your tasks underneath others by either clicking the Add Subtask button on a task or by using drag-n-drop.
Changing a Parent Task Date
The start and due dates of a parent task are based on the earliest start and due date of its subtasks. To change the date of a parent task, you must change the dates of the subtasks under the parent task.