VS 2010 Class Designer not rendering relationships correctly

Question

I'm using the Visual Studio 2010 Class Diagram designer and it does a nice job of showing relationships between a parent class and the classes that make up the properties of the parent. In the below sample, we can see that the IFoo interface has a property named Bar which is of type IBar.

However, if I add existing classes, interfaces, etc... that were created outside the designer it does not show the relationships. See sample below...

The code is all the same; and correct; but the representation on the design surface is different. For existing classes, is there a way to instruct the designer to make the correct links without having to manually recreate the items using the designer?