Thanks for this. Using Terminal I was able to open a second instance of H90 Control. I only have one H90 at the moment but I assume it will show two H90s and you just pick the one you want to connect? Is this method still working without issues? Thanks.

Yes.  It works just fine.  If you see the screenshot I posted above, it shows 2 H90s simultaneously connected via H90 Control.

I have actually connected 3 H90s now.  Still, no issues.