Originally Posted by BryanIAH
You can find the UA PNR on CO.com, but you'll need to call for PNRs on other airlines. The UA PNR is located under the reservation.
As another datapoint, I inputted an LH reservation code on CO.com, and it pulled up the reservation, including the CO PNR. It won't let me do all the things I'd like to do to the CO flight, but still, beats having to call LH to get the CO pointer.