If you have 100 objects and want to sync them, don't use Multiplayer Instance, but only Multiplayer Send + Multiplayer Receive.
Use Multiplayer instance only for the main player or when the main player shoots bullets, for example, you can generate the bullet object as Multiplayer Instance, and it will automatically be created on the other players.
You can take a look at the multiplayer car example. The cubes are synchronized across the players there.
Regards,
Cyberix3d team