Slab that spans from Top of Slab to Bottom of Slab?

[techdef]

Hi there - been stumped on this for a bit. Is it possible to create a slab style that uses 2 height datums / layers? 

 

I ask in relation to having walls below a slab which top out at "bottom of slab above", though the slab above is placed relative to "top of slab". So if you change thickness of slab, the walls below are no longer touching. It would be great if that were automagic. Engineers love changing slab thicknesses...

[Guest Wes Gardner]

Short answer, nope.  Long answer, nope.  You'll need to change the elevation of the level that the wall is bound to, if I'm understanding correctly...

[genie]

@Wes If there s a 6" step from the main house to garage, would you recommend creating a separate story (elev -6) just for garage?

I can't seem to get the garage door to insert in the correct elevation if kept at the same story as the main floor (elev 0). There doesn't seem to be a way to insert door relative to the bottom bound of the wall. or am I doing something wrong? TIA!