Creating task hierarchies can help you make distinctions between scopes of work and individual tasks.
Individual tasks in your project plan may be components of overarching parent tasks. For example, "Product Plan" and "Marketing Plan" may be two separate scopes of work, each with their own set of child tasks. Task hierarchies differ from task dependencies in that parent tasks do not depend on child tasks, and the parent task is often not an individual task itself.
In the example below, "Launch Event Plan" (Row 10) is a child task of "Launch Schedule" (Row 9), which itself is a child task of "Product Plan" (Row 6) along with "Product Use Case Definition" and "Business Requirements" (Rows 7 and 8).
Note that parent tasks and child tasks differ in the Gantt chart from typical row hierarchies. Some fields of parent tasks – like start and end dates and percent complete – cannot be edited directly, as they are functions of the relevant fields in their child tasks.
Creating Task Hierarchies
You can create tasks hierarchies for Gantt charts the same way you create row hierarchies. To indent data in a row, select the indent button in the toolbar, and that row will become the child of the parent row above it. Or reverse your indent with the outdent button in the toolbar. You can pick any cell in a row and the entire row will indent or outdent to the row above it.
Once rows are defined as parents or children with indenting and outdenting, those rows can be visually collapsed or expanded to hide or display the information in the rows.
Parent rows that are already expanded and show all child rows will have a minus sign next to the parent row . Clicking on the minus sign will collapse the children rows beneath that parent row
Similarly, parent rows with their children collapsed can be expanded by clicking on the plus sign .
Parent Cell Rollups
Parent tasks are not treated as tasks themselves. Instead, they inherit the attributes of the child tasks beneath them. For example, the start date of a parent task is equal to the minimum start date of all child tasks, and the end date of a parent task is equal to the maximum end date of all child tasks.
These "rollups" happen in Spreadsheet.com by default and make particular cells in parent rows uneditable. However, you can also use unique parent cell formula to reference child cells. For instance, you might wish a parent row to inherit each of the owners from its child tasks.
The full set of hierarchy functions includes: