How does the relationship between Projects and Sub Projects work? (Issue w/ sub project deletion)

[Ken Lombard]

We had an incident where a project was deleted.  This somehow triggered the closing of project tasks and stories of a seemingly unrelated project.  After some digging, I was able to restore the project in question and I discovered that it was actually a sub project of the project that the closed tasks and stories were related to.  I'm wondering how the relationship works between projects and sub projects how the effects of deleting a sub project would flow uphill and impact the parent.  Is this normal operation?

[Rajesh_Singh]

@Ken Lombard 

Few points

1. When you close a project, all project tasks and sub-projects associated with the project are closed automatically. Normally, you should not reopen a project after it is closed. Updating the project state from Closed to Work In Progress, Pending, or Open is not allowed. If you still need to reopen a closed project, reopen an existing project task or add a new task to the project. This action for a task moves the project from Closed to Work in Progress state without affecting the other closed tasks.
2. If your project contains sub-projects, you can close the sub-project without affecting the parent project. Change the State of the sub-project to any closed state to close the sub-project. Closing the sub-project closes or changes the state of all the tasks associated with the sub-project. Also, changing the state of the sub-project to Work in Progress, moves all the associated tasks to Work in Progress state.
3. The Copy partial project option copies a selected task and its child tasks into the project, or all project tasks into a sub-project. It also preserves all dependencies and relationships among the copied tasks and their child tasks. Any relationships or dependencies that involve tasks outside of the scope of the copied task are not preserved.