2 materials in attic wall

[ebdesign]

I'm trying to add shake siding to the upper half of a gable attic wall. Don't want to change the default top/bottom of the attic wall or the wall below. Tried the wall covering tool & making the attic wall a normal/ pony wall, etc but can't seem to get it. I can do the polyline solid thing like I have in the past, but it's a PIA, especially around vents, etc.
Is there a way to get this to work w/out the workarounds? If I leave the wall top/bottom at their defaults, then it frames right.

Jim