I don't have a license for Harness so I can't test anything. Looking at the API via Spy for Solid Edge, I can see potentially how to get the information. I'm guessing what "Show Connected Components" actually does because again, I can't test. I would expect that you will have to gather the information yourself programmatically. Here is the code path that I'm seeing to get you started.
Application.ActiveDocument (Cast as SolidEdgeAssembly.AssemblyDocument)