All this is so confusing. I thought travel on * A was going to be seamless and trouble free.

If I recall correctly, on One World, passengers can check or make modifications to their tickets at partner airlines' offices/facilities.

* A doesn't have this kind of flexibiliy. I tried to get SQ to look up a UA PNR, the girl at the PPS in Singapore told me, "We are Singapore Airlines, not United. You need to contact united to look up their reservations".