DuncanB:
Change the Wall to Floor Plan Display > Show on Stories >
All Relevant Stories, Floor Plan Display > Floor Plan Display >
Projected with Overhead, and Floor Plan Display > Outlines > Overhead Lines >
Dashed. You will then need to adjust the Floor Plan Cut Plane settings for each story so they include the wall, this should be simple for the main floor but may take some calculation for the foundation level. The FPCP is saved as part of the View, so be sure to set the correct settings there.
David