I have mainly one problem with Solid Edge ST4 (a screenshot is below):
I am creating an assembly from a part (the base plate) and another assembly (mirror mount with a mirror attached; each are parts). I have placed all the parts for a specific ray path. Now I want to have shallow rectangular excavations in the base plate so that the red part of the mirror mount fits in tight and is thus locked in position and angle. When I select the base plate for modification, I can see the mirror mounts but their edges and planes cannot be used as "fix points" to create a proper sketch. There is just no interaction with the mirror mounts.
I had basically the same problem when I created the ray path as a sketch: The sketch does not recognize the center of the mirror as a fix point. I had to make tiny holes (0.1 mm) in the center of the mirror in the part mode and zoomed in alot to align the sketch according to these holes.
I guess for an expert it is just two clicks, but I am not able to find out how to interact with the parts.