How about this workflow?
- First make a new document and name it Layout_master.
- Then create a master sketch on Parts XY-plane.
- Then make planes passing through each centerline representing a wall center. Save and close document.
- Create a new document and make a Part in it. Name the document Wall_North.fcstd. Link Layout_master into this new document. Create holes for windows using the previously created center planes as attachments.
- Use your favorite Assembly workbench and put all together, and Bob's your uncle!
OS: openSUSE Leap 15.2 (KDE//usr/share/xsessions/default)
Word size of FreeCAD: 64-bit
Version: 0.20.24992 (Git) AppImage
Build type: Release
Python version: 3.9.4
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.2