Objects attached to structural elements

Hi

I'm playing around a little with parametric cells. I've created some steel plates and can now place them through the place object tool. When I place or later copy them they're getting attached to the element I click on on placement. So when I later move my, for instance, beam around, the plates are moved along with it.

Same goes for when I add my beam to a named group, all the objects attached to it will also be added to that named group. 

Is there a way to see this hierarchy of elements? And attach, detach elements from each other? 

Regards, 

Robert