Some motion sensors do not 'play well' with fluorescent lights. Read the instructions on the box to get the right ones. They draw a few volts at all times to power the sensor and may not leave enough voltage for the fluorescent light. I wired a fan and light (not fluorescent) off one sensor, but never as complicated as your situation. If it were my restroom, I would use JoeD's approach and separate the common fan from the room fixtures. Just my