I'm using:
Product: OmniGrafflePro-5.2
Tag: OmniGraffle/5.2/beta7-138.7

Here's my desired use case:
I create a "Person" class in a multi-page UML diagram.
However, that class is relevant to more than one page, and so I can drag it into several pages so I can show it interacting with other classes in several contexts.
If I change the attributes/functions of the class, it will change every instance of the "Person" class on every page.

I'm having trouble figuring out if/how I can do this. Of course, if I copy-paste (or Edit->Duplicate) the class, they are considered separate entities so if I modify one it will not modify the other.

Thanks!
Jim