title: how to design ViewModel
body: <p>I have EF 4 implemented in the project. Within it, there are tables customer and order. Which has relationship one (customer) to many (order). </p>
  
  <p>I'm creating a viewmodel for both (CustomerViewModel and OrderViewModel) to be passed from my domain layer to interface layer (MVC in this case). </p>
  
  <p>Now the question is "do I need to reference both viewmodel? for example in customerviewmodel has <code>IEnumerable&lt;OrderViewModel&gt;</code> and in orderviewmodel has <code>CustomerViewModel</code>.   If so how do I design it (as a best practice) so that <code>IEnumerable&lt;OrderViewModel&gt;</code> and <code>CustomerViewModel</code> is populated with the correct reference?</p>