Not sure if people are aware of this, but there was a mod created that allows you to play with another friend in the same household. It's called SimSync. Here is the official website: https://simsync....
While a good idea, I think that this mod will be a curiosity at best. Sims can be quite dull and I heavily doubt that presence of another player who may not agree with you oh how to play will make the experience more enjoyable. At least alone one can play as they see fit with no intervention. Maybe it's just me, though.