Originally Posted by
sthedens
In typical Door families, the door panel itself is modeled as an extrusion in the "closed" position. This is typically turned off the in Visibility Graphic setting for Plan Views.
The door swing and panel in the "open" position are usually just symbolic lines that are drawn in the Reference Level View and thus only display in Plan Views in the project.
You'll need two yes/no parameters: "New" and "Existing". Then you need to assign the symbolic lines' Visibility to the correct parameter. Finally, you'll need to add a logical formula to one of the yes/no parameters so when one of them is "on" the other is "off". E.g., for the "Existing" parameter have the formula be "not(New)". By toggling the "New" parameter, "Existing" will automatically be the opposite.
It's up to you whether the yes/no parameters are Type or Instance.