Not an official policy per se but as a word of caution, I moved my LGA-YYZ from AA to WS after it got cancelled last night, agent was able and happy to do it. My WS ended up getting cancelled and i was completely without status or anything to make the rebooking on WS easier, and now im looking at 2 extra nights in NY as WS absolutely refuses to reendorse me back onto AA or any other carrier.