Well I'm trying to understand Revit's thinking just for that reason....I want to turn certain underlays on and then use the linework tool to set certain edges to <overhead>. When the underlay is turned off, the linework stays. Now that brings another point....I wish we could specify whether this linework acts as detail lines or model lines, as right now I have to make these changes in ALL plan sheets separately, including the "working" plan views, in order to show overhead items. Sure, I can use model lines and lock them, but I don't like that workflow. I think the the underlay should let the user choose from existing views in the project, thus giving you totla control over HOW the unedrlay looks, and also being able to pick a color/opacity.