I just found out the hard way a potential bug in the system. I have ~200 points expiring in May and thought I'd spend them on a ~$250 domestic ticket, but Shairpoints deducts the oldest points in your sharing group rather than those closest to expiry. This can catch you out if one or more members has unredeemed points from way back but qualifies for no expiry through status or some credit card programmes. I will give them a ring and see if it can be resolved, otherwise, presumably, will have to get my fare refunded, quit Shairpoints, re-purchase the ticket, and then rejoin if I can be bothered.