Aggregate child item tracked time together with parent tracked time

Let’s say I am starting a new project A with the following sub-tasks which represent the different phrases of a project

Project A

Initiation

Sub-Task (later on)

Planning

Execution

Monitoring

Closure

When I work on Initiation, depends on how complex a project is, I might not necessarily break it down further (or I might not know enough to break in down further), so I will start putting comment in the initiation and start tracking time I spent in the Initiation phrase. And maybe 2 weeks later, there is a particular tasks / roadblocks which should be under Initiation, I will then add that sub-task in and want to track the time I spent with that sub-task in particular. Now at this stage, there are time already tracked in the Initiation task, which will then stop the time tracked in Sub-Task (later on) to be reported to the root task.

So might be a feature could be turn on so the Tracked time from different levels could aggregate to the Top Parent Task. Same as the Parent / Sub-Task Re-scheduling, there could be another feature saying that by turning on, then changing the parent schedule will not affect on the child tasks