It's all moot because any electrician installing 3 switches in the basement for three lights in the attic, would have installed 2, 4-ways in the attic stairwell just to jumble the order and keep things interesting. 2 of the basement switches would be able to be switched to control any of the three bulbs while the other could switch 1 of 2. It could be a great shell game for the kids.
Joe
