Sloped Ceiling Over Open Below Space?

[MrMooCow]

I know what I want to do.  I have no idea what the technical term for what I want to do is, so I can't figure out how to explain to the software.  

 

I have a two story building.  There is nothing above the kitchen, so I want to have the hallway above look out over the kitchen.  My thinking is to have the 2nd story ceiling come out flat 5' from the railing, then angle down to meet the 1st floor ceiling.

 

I know this exists in real life, as my sister has exactly this kind of thing in her house.

Some help on how to get the software to do this would be appreciated.  Thanks.

[Jo_Ann]

If your 2nd floor walls above the kitchen (left and right), are not set as 'gable', then you will have to add a sloped soffit to serve as the vaulted ceiling.

 

[MrMooCow]

I'm using Home Designer Architect 2023.  Signature changed.

 

So the gable sort of does what I want, but not quite.  I want the height of the walls of the sloped section to go down from the full height of the second floor to zero at the "top side" (top of the screen in my picture).

 

I did search the forums, but found no help there.  That may simply because I don't know what this is even called.

 

Thanks for your help.