Just chiming in on an architectural principle I have adopted over the years that I tend to apply in answering this question: 

Don't mix the taxonomy with the entity you are managing.  

For the specific question, what does a child mean?  Does it mean, decomposition, or is it a dependency?  You need to be specific in order to effectively manage things.  

I discuss this situation in an APM blog a long time ago, applying the same principle works here just as well.