Hi Tim,

You need to create a wall with height enough to fit the window

Try this
- For all the wall: You can delete the wall of the upper floor, and make the lower level wall with the height of both floors. In this way, the window will stay between both levels.
or
- For the window segment: Using the "wall break tool", cut the segments of the wall (1st and 2nd floor) exactly at left and right of the window--> delete them--> create a wall segment with the same width, but with height of both floors--> the window will stay between both levels.

Hope this helps

Patricia