This is an issue that comes up time and time again and there is no simple answer to it, it's just how Windows is with USB ports and controllers.
Now having said that, I was reading an article about setting up dual flight sticks and throttle for Star Citizen a couple of a nights ago and of course having that many controllers is a nightmare due to how Windows deals with this stuff. This article goes over a lot of stuff and several programs working together to work out the issue but apparently it works. I have no idea if this same stuff would work here but in theory I would imagine it would.
Here is the article so take a look at it and see if any of it works out for you.
https://ventorvar.com/posts/joystick-intro/