Hmm, since you left your wiimote at your bro's house then it should not be able to read it, so when you try to sync the wiimote that's normally P2 it should become P1...or so I would think...
You can switch between the 2. Whichever remote you want to be number one, use that remote to turn on the Wii and when it says PRESS A, press A on that remote and it should be number one.