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move /y "C:\Users\Junk....\my_first_characters.bin" "C:\Program Files (x86)\..POL Junk..\usr\all\login_w.bin"
As a batch file would replace the bin file automatically, though Windows 10 permissions might get mad about moving something in PFiles; I was able to bypass by running as admin. Could make a batch file for each potential bin file...or write a single more elegant script that just asks for input on which one you want to move.
Could even add:
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TIMEOUT 2
START C:\"Program Files (x86)"\Windower4\Windower.exe
To the end to have it launch your first POL instance for you (TIMEOUT 2 adds 2 second delay to make sure it has time to move the file but may be unnecessary).
Not really trying to argue either way for/against bin-ing or using foreign clients, as these steps weren't included in my initial recommendation, but I feel this would make them about the same since once the initial setup work is out of the way both options only require you to click something.