Move highest or lowest vertices on the same Z axis using it's normal

Hey

My end goal is to make it easier to create a TIN surface in Civil 3D. These can’t be created with points in line with each other in the z axis, or points creating an acute angle. I’m wondering if there’s a way to move all of the highest points, that are in the same z axis, slightly ‘in’ so the angle is no longer 90 degrees or acute, but obtuse. (or bottom out)

The file imported will be a .dwg of vertical walls.

It’ll then be combined with another file that’s just the ground surface and a TIN will be made from the points of the two of them, just fyi.

I’ve tried following this type of thing

but firstly, it misses some points, and I can’t figure out how to separate and move them from there.

Quite new to this software and this is hurting my head trying to figure out a good way to do it.
Would love any advice :slight_smile:

Thanks!
ExampleWallFile.3dm (19.1 MB)