You could make it with a slab and save as object. Put a hole in it large enough for your window opening exactly as you would form it. Put a section of wall in your opening and insert window.
Gerald Hoffman
“The simplification of anything is always sensational” GKC
Archicad 4.55 - 27-6000 USA
2019 MacBook Pro-macOS 15.0 (64GB w/ AMD Radeon Pro 5600M GPU)