How to make a Variable in a Blueprint Accessible in other Blueprint

I ended up watching it again and figuring out how to use casting. Unfortunately, what I was attempting to do yielded the same results as the way I was doing it originally so I just removed it. If you know, can you explain to me how multiple characters can control one object at a time. I tried setting the functions to send to server and then the server would modify stuff but it just ends up with there being two instances of what is being done. I’m trying to spawn/despawn an object but I’ve also tried spawn on level and change visibility and they both make two instances for each of the two players.