first: wear caution if you do not have a PS/2 port on your machine, because you can lock yourself out. It has happen to others 
just in case: backup your important stuff and verify the backup (there is an option there to just check without restore)
check in the original sys-usb the controllers you have there. If you have more than one, you can detach one and attach it to your new disp-sys-usb.
at this point you will have 2 different sys-usb. if it works, you can probably take the other controllers and attach them to the disposable sys-usb (again check what controller is your keyboard plugged to)
regarding “no strict reset”, just play with it a little in your original sys-usb to get to know what you need. if possible do not enable it, but that is unlikely