I just ended a project where prefab walls were joined like this in the reality but I agree that was not something common.
Sure. My idea was to perform a boolean fusion of all the walls when outputting the svg to techdraw, but for every other use keeping them separated. I have no Idea how complicated it is to suppress the representation of that seam, since at the moment the viewprovider code was provided by @realthunder and it does simply represent the Shape in coin. I dont really now where to put our hands, and if that's something that worts the effort.So, to truthfully represent the model in UI, when unselected, this join should appear to be seamless.
You can easily produce all those join types by hand, if you show all wall hidden properties you will realize that you can control pretty much everything .If we want to model joins, there should be multiple types:
This is not just complex... it's COMPLICATED indeed! I don't know if those softwares just produce a 2d joining or modify a 3d solid too... I guess the first.And it gets complex with multimaterials:
Anyway what I was thinking is to just cut 45 degrees all layers and do not bother at all about if those layers would join or not. And provide a command to convert every layer in a wall subobject, so if the user really needs to make every layer match, he can do it by hand, keeping the wall global functions like window hosting and subtractions.
But i'd really like to have suggestions on this topic. Just remember FreeCAD is mainly a mechanical cad, so I do not think it is generally a good idea to take a too different path.