I do appreciate the input and effort, panthony.
I assumed that if you had to, you could insert these components separately, but if you have a hundred fifty (or more) to do, it would be nifty (and expected) that you could make one symbol to do the dirty work, or at least to limit it. The key is to use the custom window PIO option and to make it two windows wide. The louver, inserted in its separate wall below the window, can be made to look rrealistic, with some fiddling.
Thanks, Robert, for joining in. The problem seems to have been avoided as per the above.
It only took a few hours to figure out how to do multiple windows. The documentation - is it there? I could not find it. Now that I know, the window tool seems very powerful, but I still feel frustrated that it took so long to do what seemed to be a simple application of a PIO and symbol.