I sometimes select and edge of a solid and convert entity. The resulting converted entity is a spline. I now find myself in the position where I need to edit the shape of the spline that was created. I delete the on edge relationship. After doing so there are no control handles or points on the created spline. Is there a way to "convert" this spline so that I can edit in a meaningful way?
After you delete the on edge relation, right click again and choose "simplify spline". This will add control points and handles back to the spline. From there you can do anything with it that you can do with other splines.