I've had AA codeshares and QR and BA post before I've even left for the airport on day of departure. Once was last November on QR DFW-DOH and the other was in December DFW-LHR on BA. With the BA flight, I ended up getting re-routed on Delta into LHR due to a mechanical issue on our conncection into DFW. Didn't even need to call and request original routing credit for that flight as they never took the posting back lol.