True. Until you change layer sets. Then you start the wheels turning, just for a simple task. Who's on first, what's on 2nd.
Every layer combination can have different Intersection Priority Number for each layer.
So in one combination you turn on the foundation layer with an IPN different to the other wall layers so they do not intersect.
In other layer combinations if you do not want to see the foundation walls then you turn off the layer (still with a different IPN).
If you happen to want the foundation walls to interact with other walls, then just set the IPN the same for those wall layers and save that as a new layer combination.
It sounds like you just need a plan layer combination that shows the foundation wall layer and all section, elevation, 3D and other plan layer combinations (basically all other layer combinations) to hide the foundation wall layer.
The foundation layer should have an IPN different to any of your other wall layers in ALL of the layer combinations so they never interact with anything else.
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