The following is a simpler description of my problem:
I am using EA to build a Business Process Model. My process descriptions consist of Activity diagrams where I show the activities that make up the process and the flow between them. Since activities can be "re-used" in other process descriptions - they are commonly used - if I use flow links between the activities, these appear in all such diagrams that these activities take place in. However, the flows between these activities can be different in different process diagrams. To solve this problem, I used an instance of an activity (which is now an Action, for some reason). I want to show that different instances of a standard activity can show different relations (e.g. flow) when they are parts of different processes. (Did I say I was going to give a "simple explanation? )