In the program I pasted from (ToDoist) the user has two choices for treating parent tasks:
Choice 1: You leave the parent task as task (with a checkbox). Subtasks can be added under it and the section is fully collapsible. Marking subtasks as “completed” has no effect on the parent task. Marking the parent task as completed, however, makes all subtasks automatically completed. If one of the subtasks is then uncompleted, the parent task is marked also as not completed.
Choice 2: You end the name of the task with a semicolon (like in Asana). Then, the parent task loses its checkbox and becomes a simple section title. Completing the subtasks has no effect on the title (it’s still sitting there). There is no way to mark the titile as completed.
I made a short video: Video Task List