Solid elements operation - Overlaping elements

[Titiriga]

Hello,

I'm having trouble with Solid Element Operations (SEO).

I have two walls. The upper wall is an exterior façade wall, and its top and bottom are in contact with two roofs (not shown). The lower wall is an interior wall separating two areas with roofs at different heights. The blue mesh is an SEO operator that will be hidden.

What I want is for the top of the lower wall to be trimmed by the blue mesh, while the bottom of the upper wall to also trimmed by the same mesh.

The problem is that, after performing the SEO operation, the upper wall also cuts its own volume out of the lower wall. This is not caused by SEO, because the two walls do not have any SEO relationship with each other. It appears to be a building material priority issue.

Both walls need to remain on the same layer. Their composite structures are similar: the upper wall uses the same composite as the lower wall, with a few additional layers on the exterior side.

What can I do to make the walls intersect correctly, so that the upper wall is not automatically subtracted from the lower wall?

Thank you in advance.

Operating system used: Windows

[Mathias Jonathan]

You can have each of the walls in a separate layer with a different intersection number for those layers.

[Titiriga]

Thank you, Mathias. That's what I'll eventually do if no other solution comes up. I know it would solve the issue; I just don't want to create a separate layer just for that wall. Also, changing the intersection priority of a layer that contains other elements would affect those elements as well, and I'd rather avoid that.

On the back side, both walls in my example are coplanar and have the same finish. Using this method would create a line separating them, even though there shouldn't be one.