i have a flight from GRR to ORD on united, ORD TO VIE on austrian, VIE to PEK on air china, and PEK to WNZ (domestic connection) also on air china. It's all on one united ticket.
I actually called air china regarding the checked luggage, they informed me that I do not have to pick it up in beijing. I'm having doubts after reading your comment. It sounds like i would have to pick it up in beijing and recheck it/