How to Model a Window with a Nailing Fin

[genarch]

Hello, not sure about the rest of you but the typical windows I'm using have nailing fins and I've tried to model this condition in Archicad (27 USA Library) but I've been unsuccessful. Does anyone have any tips?

Here's the problem I run into: I cannot find a way to have the window frame protrude 1-3/8" from the face of sheathing as it would with a nailing fin installation when using the Stud Wall with Siding wall closure type. If I use a custom wall closure, then I can have the window protrude as it should BUT the window casing overlaps the window frame.

This is what my windows typically look like in plan view, notice how the face of window aligns with face of sheathing.

This is how I'd like it to look in plan, with window frame extending beyond sheathing and casing butted up with outside of frame.

Section @ HeadSection @ Sill

Here's the section view at head and sill. The sill should look like the head condition, but the casing overlaps the frame. It's also worth noting that, in my custom profile wall here, the casing is actually not flush with the face of sheathing although I set the opening reference at the face of sheathing. In plan the casing looks correct but in section not so much.

Section @ HeadSection @ Sill

And here's how I want them to look which more accurately reflects how they're installed. Anyone got any good tips?

Operating system used: Mac Apple Silicon 14.5 Sonoma