Be prepared for an unpleasant surprise if you ever fly tpac with AC and expect them to interline bags on separate tickets . They have a published policy not to do it, and I found out the hard way, though I once got away with it in PEK (where AC checkin is staffed by CA).

There are also reports that LH will (sometimes) not check bags on separate tickets, even if they other flight is on LH!! In any case, my point was that the ability to do this at checkin sometimes depends on exactly what type of agent you get. I've had UA agents give me a hard time on occasion with a UA->UA transfer, usually because they have never personally done it before.