Question regarding Topic's/Hierarchy

Greetings!

Is there a way to group objects together as belonging to a certain theme without having connecting lines between them? (Something Topic’s do)

For example, say I wanted to create a diagram that had cars, boats and planes. I can logically divide similar object types into layers. Great. But what if I have blue cars, red cars and green cars and the same for the other categories. I want those to be in their own layer (or something like that), but I want all cars to belong to a global group called cars. the same for boats and planes. I want a parent grouping that would include all the sub-groups that reference color to belong to the parent.

Is this possible?

It doesn’t appear that separate canvases nor layers do the trick. The closest thing is topics, but then I have this unwanted connecting line between the parent topic and it’s children.

Thoughts?

Thanks!

Steve