It sounds like your A B C D spreadsheet might be an intermediate step since you are importing data into it. Where is it coming from?

Based on what you have said, I would create a template that referenced the A B C D spreadsheet with a simple =. Highlight the range A1:Axx in your second file. Type =, then highlight the range C1:Cxx in your first file and hit enter. Highlight the range B1:Bxx in the second file, type =, then highlight A1:A1xx in the first file and hit enter. Even if you don't know the exact number of rows, if you know it will be less than, say, 100, just make xx = 100

Save the second file. Assuming you can always import data into the first file without changing its name you just have to open the second file and it will read the first. Save As this month's report or whatever you want and you are done.