does every component resource need to link back to an assembly resource?

This is more of a question than a definite issue. Right now (WD32) the 'component' resource requires a link back to its containing 'assembly' resource (in the 'assembly' attribute). This makes sense for the first-level components (i.e. the components that are directly referenced by 'assembly.components') but what about the second, third, etc. level components (i.e. the ones that are referenced by 'assembly.components'->'component.related_components'). Does it really make sense to have every member of the component tree reference back to the top-level 'assembly' resource? What about components that appear in the trees of more than one assembly? Which 'assembly' resource should they link back to?