Multiplayer is only an illusion of the player existing within the same environment as other players. Fundamentally multiplayer is very similar to single player in the sense that the level, items, textures etc etc, are all loaded up and used in the same or similar way.
The only real predominate difference between multiplayer and single player (apart from the games play style) is that multiplayer games will send and receive packets of information between the computers of those who are playing, so that a players environment and statistics can be updated so they are the same as what other players perceive and vise versa.
Generally the best thing would be to make a separate hand model and "attach" it to the camera.
That we simply are has allowed this reality we call real from the power of intangibility to pull out of inertness action, chaos and hold it into its form we call matter.