Wednesday, September 15, 2004 07:40 AM
Usually Usecases are modeled for different scenarios. So, basically you should scope the scenarios and draw usecase diagrams for each.
In your case, if "Customer call in to make order" would be
CUSTOMER Actor -----> Call in(Place) Order Use Case
CLERK ACTOR -------> Process Order Usecase
When you have the whole scenario worked out, you can tie them all together.