I’m developing a city landscape for historical and hobby use. There will be a lot of buildings and several districts. I don’t want to repeat the windows and doors and in the same size houses or buildings. Then it would look generic and unprofessional. I also hope to open a museum with 3 D buildings but scaled down such as in a “Model Car” The sketched layout will be a roadmap for my Museum to develop actual buildings and houses inside the Museum building, similar to what a planetarium tries to achieve
Why don’t you create component collections for the windows, doors, and other architectural elements and then bring them into your models as you need them? Much simpler and you don’t wind up bloating your file as you did with the one you shared.
I’m using the popular extensions “Val-Architech” and “Flex tools” extensions. And I did find Flex tools has an option to save specific version of a window or door design. Then retrieve it from the its own library for future use. I just haven’t worked with it enough to be familiar, For now I’m doing the best I can by trial and error. I think the easiest for me now, is dividing up my files into sub-files and sub-folders through splitting up each task, i.e., originally I used to bundle an entire project in a single file. And found it is too much for the file. I will transfer the windows and doors (on the wall pieces ) to the main file (where a district of the city is ) and do the final assembly,
Since I have volumes of buildings and several districts, I think this is the most streamlined for me
Seems to me that you could learn to use the native tools for saving components in local collections and eliminate the trial and error but it’s up to you.
OK. I still think you are working harder than you need to be but as they say, you do you. 
Very much appreciated !! Thanks for your wonderful help. I definitely will learn this and other options for apply this correctly. I’m just trying to get through the major part of my project. When I’m in the phase of fine tuning the displayed models, I’ll try to devote more time to taking advantage of the menu items.
Thanks