Are you using the stair tool (21 &22)?
If so you can use Solid Element Operations to trim your wall (won't show in plan of course).
And if you select the 'Boundary' of the stair in plan or 3D you can adjust the shape of the stair - or just adjust the width of the stair flight in the settings maybe?
Barry.
One of the forum moderators. Versions 6.5 to 27 i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10 Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11
Here's a stair I recently created with a skirt wall. The wall is a panel placed at the bottom of the railing. I set the elevation of the panel element from -3" to -11'. The bottom of the panel goes into the ground; I could use SEO to trim it if I needed to.
I had to cheat on the texture to keep it vertical, as the panel texture of a rail object follows the slope of the rail (see the white diagram). I created a copy of the surface texture and gave it a slope to counteract the slope of the stair. I applied this texture (in edit mode) to only the sloped segments of the rail.
R Muller AC 28 USA (20+ years on ArchiCAD) MBP 64GB Apple M1 Max OS 15 Sequoia