[Nyx]

As far as I recall, electricity takes the path of lease resistance. Therefore, just a chunk of copper in there would result in a short to ground, blowing the fuse (you ARE using fuses, right?).

In fact, what I think ACTUALLY would happen looking at it again, is only lights 1 and 2 would light.

Yes electricity will take the path with the least resistance. I'm not sure what a fuse is since I'm taking all my science courses in French, but Google is telling me a fuse is a resistor and therefor the lightbulbs function as the fuse (please correct me if I'm wrong). I'm just unsure if taking the bulb out and replacing it with copper would result in the battery being short circuited and making the battery melt, or if the circuit would function as per usual and just the other batteries (minus 1 and 2) would just stay out.