By logic, if everything is a component or group ("shape" doesn't describe anything) and you have only one edge left, it doesn't belong to anything else.
What is 2 and 3? One problem you might have is if your friend drew anything on other layers. All edges, arcs,cicles etc. should be drawn on Layer0 in fact Layer0 should always be the active layer. You can check this by editing the components and select different edges to see what layer they are on. There's a plugin (should be built-in) called "default layer geometry" which moves all selected geometry (edges faces etc) to Layer0. It's very useful. It leaves components on the layer they are currently on and it operates on geometry both outside and within components (you don't have to edit or "open" the components to make it work). I would usually run it on files I get from others.
you have a line in the Outliner?
