Building walls that have alcoves

[Dewin]

I have built a wall for a room. Attached to that wall on the outside of the room (in the hallway) I want to build another wall that attaches to the room (first) wall. The second wall would have a pass through window so I can see the back of the first wall and create an alcove like shelf. Into that alcove I will be placing large pieces of art work. When I build the two walls separately and then unite them the pass through window goes through both walls instead of just the one in the hallway. Is there anyone who can tell me what I am doing wrong? Thanks

[Keith_K]

Can you take a screenshot of your drawing and post it to this thread so that people can get a better idea of what you are trying to describe? It would also help if you state what version of HD you are using. It helps if you put the latter as your signature.

[Keith_K]

Is this the sort of thing you mean?