If that was the issue then doing two separate user accounts on the PC, then having a primary steam account (the existing one with all the games) and a secondary new one, and putting them into a Steam family together just like the person I replied to said would be functionally equivalent to yall having two separate PCs with your own steam accounts when it comes to saves and steam achievements and stuff, but you only need to buy and install the game once. It’ll also let you have separate config files so if one person like controls bound one way and the other another you’re not having to rebind each time yall swap who is playing and everything.