Good, now you need to find out where the other switch goes. First thing to try, which is easy, is see if it is tied to an outlet(s). Beside a master bed area (think lamps) and under windows are good bets for that sort of thing. In which case it would likely wire half of the outlet. Flip a coin as to whether it is the top or bottom half.
Right before my parents moved into their house two years ago, the hurricane came through. We didn't know it, but the roofer didn't flash the chimney properly and supposedly it is too sharp of an angle to support a 'cricket' (?? - don't get that ??). Anyway, it had been leaking slowly a long time and we didn't know it until the storm came through. Walking into the great room, looking at the fireplace, I asked, why is the stone all wet, then looking around, why are the ceiling and walls wet, why are all the joint tapes falling down? Ugh. Anyway, the front outlets under the windows are half switched and the switch is in the closet by the front door. This is for xmas lights or what not. Well, my dad was trying to do something and plugged into an outlet and it didn't work. He started blaming it on the roof leak. Huh, what? I finally went out there, had him plug his device in and show me it didn't work. I then had him plug it in the bottom half of the outlet and it did work. I then flipped the switch and had him try the top, showing him it worked. He still blamed the roof leak and called the electrician. SMH.
