Clarity

when we create a sub project the parent project will have the dummy task of child task in parent task's list.

can we edit that data from parent project?

can we add resources to that task or remove resources from child task from parent project?

Check this:

Using Effort task in Workbench 

NJ

And this:

Can you post time against at the Project level instead of the Task level? 

NJ

 we can post time against task only right..

can we edit child task duration or edit task status. From Parent Project Page

Its not a "real" task, its there to support the sub-project only.

Yes David Morton its a dummy task which will be created, when we create a project.

Even for that task we can assign resources, enter time for it. 

But in some situation i can edit the data of that task, so i want to know reason when we can edit and when we can't.