CakePHP 4 - Tree Behavior BOM Bill Of Materials

Hello. I am trying to create a BOM by applying tree behavior to make things easier. Has anyone been using it for this purpose?
I see that in the examples they always put together simple menus and they work well. I tried it.

But making a bill of materials is a bit more complicated. I have to create many different trees in the same table. (I saw in the documentation that there is an option to use a different scope) Trees should be able to reference other subtrees as well. (Assemblies with sub-assemblies with sub-assemblies and so on).

And what I find more complicated is being able to calculate the costs, since I have to start with the deepest sub-assemblies and work my way up.

The example I am using is building a PC.

1 computer
__1 motherboard
__2 memory module

In this case the sub-assembly would be the memory module.

1 memory module
____5 chips
____1 PCB

I have an Items table and a boms table.

I have read a pdf from Joe Celko and honestly I ended up more confused than at the beginning. LOL.

Any help is welcome. Thank you!