There are a many problems with your script which to the point you gotta be asking yourself “Is this REALLY a good Idea?”. But basically you could have a RemoteEvent which you can fire to all Players. That Remote Event then moves the NPCs on the Client using TweenService.
They wouldn’t since TweenService ensures that the tween is completed in time ( also you would only fire the remote event to where you want the NPC to move ). TweenService is for context a Service which allows you to change a property smoothly ( like a number going slowly to 10 ).