Window Stool Above Window Frame?

[cwrm74]

Is there a way to force the window sash to fall behind the interior window stool? Chief seems to only allow a sill, with the top even with the top of the frame window frame (and bottom of the sash).

 

I searched and saw quite a bit of discussion on this topic from several years ago, and was curious if either this has been fixed (I can't find a way to do it) or if anyone has a trick, short of manually placing a stool on each window. 

 

Here's an example of what I've done in Chief, with a custom interior sill, vs what I would like to create.