Prefab to Maintain 'Connection' to Original

[Monkey Frog Studio]

Currently, after creating a prefab, there's no 'connection' to the original. What I mean is, I can make changes to the original models still in the scene and the prefab does not change to match. Why would this matter? Let's say that I create a prefab of a hall chunk that contains a floor, two walls, ceiling, model of a light, and a point light. I use this to create several hallways very quickly. Then, after testing, I realize the point lights are too bright or too dark. I can select the point light in the scene panel within the prefeb, but I cannot change it (i.e. the brightness of the light, the color, etc.). If I go back to the original (non-prefab), I can change that, but that only affects the original and not any of the prefabs. 

If the original from which the prefab was made could be stored and changed, affecting all prefabs, this would allow for quicker editing, I think.