@hammax @paulee Thank you for taking the time to further enlighten me. I am going to understand and try your suggestions and further look into the topic to find out which way works best for my purposes. In principle, I wouldn't mind if changing dimensions after initial modelling wouldn't work becaus...

@meme2704: Thank you very much for taking the time to reply! I tried to create the walls the way you suggested and always created the blue reference helper lines from the previously merged wall. Placing windows now apparently does not disturb the wall references anymore! However, it seems that I can...

First, I am very inexperienced with FreeCAD so I reckon this is a PEBKAC case: When I place multiple windows in my wall (walls are created based on sketches), the walls of the whole building become weirdly shifted and I do not know why. The change is immune to undo operations. When placing a window,...