No, you can't use one FP for two people. The CMs are pretty careful to collect one from each of you as you go through the queue.
OP, I wonder if the CM meant the fact that once the return window on your FP arrives, you can pick up another FP for BTMRR or any other ride-- and hold them to use for later. Because you can use FPs until the end of the day, not just within the return time. That's why so many DISers just collect FPs all morning, take a break, then come back and use them all right in a row in the evening when the lines are long. Many people around here like to pick up 4-6 sets of FPs in the morning and use them all later.
The rides that are disconnected from the network on a regular basis are Roger Rabbit's Car Toon Spin in DL, and GRR in Cal. Adventure. Plus the two parks are disconnected from each other.
BTMRR goes off network once in a blue moon. Happened for a week or so this summer.
For more details and researched information about FP, tips and trick and quirks in the system, check out Hydroguy's FP use threads here:
http://www.disboards.com/showthread.php?t=1520483
Hope that helps!