Support for multiple levels in project-plan hierarchy

Having multiple levels for organizing plans in, would be a great advantage.
Now you can only configure plans for a specific project, but in our environment we have lots of components for the same project (which is in fact a sub project of a larger project).

As project doesn't have much properties or configurable items, I don't expect it to be much work for introducing multiple levels of them, as they only serve as container for holding plans, but of course I could be wrong