Selecting edges of sub-objects in groups or components in Sketchup is very time consuming ,edges tools (Select Edges in Objects) for faster manipulation, and also support edge-related commands
Tutorial video:
Steps by steps :
- Select the current edge
- Select the edge that is hiding (hidden)
- Select softened edge
- Select unsoftened edge (unsoft)
- Select smooth edges
- Select unsmooth edge (unsmooth)

Select edges tool in Sketchup