In the example the multi-level tree consists of engines comprising modules and submodules: Engine(Parent)-Modules(Children)-SubModules(Grandchildren). The goal is to calculate the total energy consumption from lower level to higher level. Moreover, if a higher level record is deleted, all related records will be deleted automatically.
The detailed description of the adjusted functionality you may read in the Multi-level tree of related records blog post.
Any support materials, such as spreadsheets and real-life work samples would be very helpful as they would help us better understand your business process.