If your mother and SO has already gotten Solitaire LIfe on SQ< they might as well go for the Marco Polo Club on CX. The ONLY problem is that the program is only linked with AsiaMiles and they have a crappy award schedule.

There isn't so much as promo now on CX on any program except for the AA promo but which you must have a North American address and originate from NA to HK, and the 6 sector in F/J class for an additional 10K bonus after that.

Any of the oneWorld partners can give you options. But if it's maximum miles you're after, then take Swissair's Qualiflyer program. They award x2 for First Class travel.