Grouping deliverables by parent project not sub project

We are trying to build out a dashboard that displays all deliverables (project custom item type) for the top level project.

We don't necessarily care which sub project they are part of when reporting to the executives. We just need to see the health status of the 15 deliverables for the project.

The closest we have been able to come is to group by location, but that only goes one level up. Our projects can have 6 or more sub projects (and the deliverables are within the sub projects), so the deliverables on the dashboard are grouped into 6 different categories for each project. Multiply this by the 10 active initiatives in the system, and the executive dashboarding gets really messy.

Ideally there would be a way to mark the top level project as the "parent project", then group the deliverables by the different parent projects.