How do you generate a report for ALL work items under sub-projects under parents?

I’d like to be able to generate a SINGLE report where you can see ALL work items (milestones, tasks, and projects) under a group of sub-projects (2nd-level) under a single parent (top level).

This should describe the relationship I’m talking about:

Parent -> Sub-Project -> REPORTED WORK ITEMS (Milestones, Tasks, etc.)

I know this “3-tiered report” can be done if I build a dedicated report for milestones, tasks, or projects. However, it would be ideal if all three types can be compiled in such a report. Can this be done?

Thanks!