Window Casing on Thick Walls

[jakubgalczynski1]

I am working on a new home that features thick passive house walls. I'm trying to show a 1.5" thick trim / casing that extends 2" past the wall finish. 

I'm hoping to achieve this with the 'Casing' options. Everything looks good (jambs and header), except the sill. The window sill starts from the wall finish and not the window frame. Why is that? Any suggestions would be helpful; otherwise, I might need to draft the trim manually.  Please see the image attached. 

Operating system used: Windows

[Lingwisyer]

When asking about doors, windows or objects, it is advisable to provided details such as the Object Name and Loaded Library. Is this window from the AC28 Monolithic Library? Assuming it is US?

Ling.