Interesting question. I know for international-to-international most KA/CX ground agents would recommend against a through check for the simple reason that.... the passenger has to go through immigration and customs in BJS / PVG even for an international transfer. PRC airports were not designed with international transfers in mind and baggage handlers, even seeing interline bags, would ignore them and load them onto baggage carousel. It would be interesting to know what domestic-international transfer would be for the bags.