Breadcrumbs, DataView, and Grandchildren: Filter to show all notes with the same grandparent

I have a Goal Hierarchy setup in Obsidian.

I want to review a part of it in Projects. Here is the relevant section of the Hierarchy:

Mission
Assignment
Task

I want to review a particular Mission in Projects so that each note at the Task level appears as a Row.

It's easy to filter for Parent. Just do "Up = 'ParentName'"

But I am looking to filter for all notes with the same GRANDparent.

Any suggestions on how I can do this? I am very new to this kind of stuff.