Glad to hear you got your computer situation squared away, a lot has changed since your last comment!
So currently local multiplayer isn't something I have planned for launch at this time. I don't like ruling anything out this early in production, but there are some logistic problems that I'm not sure I'd be able to solve without hampering single player development which is the core of this game. Thanks for the question tho, I hope you and your sister continue to enjoy the game!