Due to security reasons, I doubt this will work...
The only time that CX might do that is when you're already tagged on to a CX flight but due to a delay or cancellation of a flight, you are rescheduled onto another carrier. Then CX will contact their baggage services to retag your bag.
If what you say is true by any means, think about it, by the time passenger has gone to the transit desk, his bag might already be on the carousel.. and what? CX is expected to wait and check all 300+ pieces of bag for that one bag to transfer? CX won't even do that for DM / First members. Don't think so.
Be real ! Be realistic !