Keep subtasks with their task regardless of sorting or grouping

When on the page for a project, in the tree view for the list of tasks, sorting by date or grouping by date or other criteria, separates out the subtasks in the sorting or grouping. For example, with a list of task, some of which have subtasks and where the tasks have due dates but some or all of the subtasks do not, sorting by date separates the subtasks into unscheduled. It is better that the subtasks remain with their tasks regardless of the sorting or grouping. The subtasks follow the task they are a part of when tasks are sorted or grouped. At least there should be a user setting to allow for this. That would be most useful. Thanks!