My goal is I'd like to play 4 instances of Fallout 76 at same time on same screen with a different mouse/keyboard controlling each instance. The monitor is 4k resolution and I can run the four separate instances as windowed 1920x1080 (or smaller).

I want to emulate how we used to play Halo and other games in splitscreen on same TV back in the 2000s before the games/consoles quit supporting split screen.

I regularly run 4 instances of FO76 (4 different accounts) no problem on my PC without Aster, but then I'm alt-tabbing between screens. I haven't setup Aster yet, but it looks like the most I'm going to be to do with Aster is 2 instances on two separate screens since it looks like mice/keyboard get tied to a screen. My hardware limitation is that I'm using a Shadow PC, a high end virtual PC that get's streamed to me from a server to my laptop. Because my laptop can only support the native screen and one HDMI output, I'm limited to two screens, but the 2nd one can be a 4k display which is why I'm interested in a solution that might be able to split the 4k display into 4 virtual monitors or any other solution that will let me tie separate mouse/keyboard or game controllers to the 4 separate game instances showing on that one 4k display.