You may use the free key-remapping product
AutoHotkey.
Here is a script for converting Shift+( to [
.
It can easily be modified and extended, as I'm not sure that I have not
understood the question in reverse.
(::
if GetKeyState("Shift")
Send, [
else
Send, (
return
After installing AutoHotKey, put the above text in a .ahk
file and double-click
it to test. You may stop the script by right-click on the green H icon in the
traybar and choosing Exit. To have it run on login, place it in the Startup group at
C:\Users\USER-NAME\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup
.
Some AutoHotkey references: