Knee wall

[MikePreble1]

There are several solutions, each with good and bad reasons to use them, because some of the steps have consequences that may matter (or not.)

This picture: I drew all railing walls.

For the stone wall, I made that railing wall invisible.
Then I drew a polyline solid in back clipped cross section and shaped it.
Then, in plan view, I moved it into positions and sized the width appropriately. I had to move it in/out/up/down a bit to make sure the existing railing walls didn't bleed through.

The question is: What do you want to show?
Homeowners want to "see" things. Sub-contractors what to "know" things.
Mike