My two brothers are flying LHR-SIN-SYD on SQ in raffles class (booked in J). Neither of them have got membership in any FFP.

I am planning to fly SIN-ICN end of the year (around dec 15) and I am thinking instead of wasting all the miles by not joining a FFP, they might as well and maybe I can get a free award ticket.

I am also planning to fly NRT-PVG at some later stage.

Which *a FFP would allow me to do this?
I checked out Krisflyer but to me it looks like the amounts of miles earned on their trip is less than require for this award. AirNZ's FFP would even in business class, but they're not elligible to enroll as they're residents of Norway. Air Canada's Aeroplan looks promising but I'm not sure of the rules. UA Milage+ looks like it's possible with a saver award, but I am not sure how easy it is to get hold of an award ticket with this ticket type and this routing.

Anyone got any suggestions? Thanks!!