Here's the analogy: I have an organism which is composed of cells which can be further composed of a medley of attachments.
What I have currently is a sort of event chain between child/parents to handle attaching and detaching components (which could affect anything along the chain) which doesn't involve ecs at all, they are functions in the entities.
Now I've used event components already (for mouse events on objects). If I wanted the system to be pure, would I create an attach component when I attach components etc? Even then how would I get all the necessary recipients to the system that consumes the component? Is it even worth it to handle it this way instead of a chain of functions? Is there a better way?