My mate booked a 6 person chalet and all her friends dropped out, my 5 mates and I are taking her 6 berth now, thusly our 2x 3 berths are up for grabs. She wouldn't want more than face value and would probably be willing to negotiate to get some dough back and not be left with a bill for a 6 berth.
Whats worse for her is that she isn't even going now. If people want to chalet share or have a friend of a friend of a friend then please let them know about this. Its a shame for the girl.
Contact me on this if you are interested.
She might even look at selling it to just 2 people or 1 person if it came to it, its better than nothing at the end of the day.