If my memory is correct, then the XAJH era is a few centuries after the ROCH one and somehow a successor of DGQB, Feng Qingyang, is still around. Therefore it means during ROCH time, one of Dugu's diciples/successors must still be alive somewhere. Why didn't he show up at least once? Considering Dugu's power, his successor could easily become one of the Greats.
The Divine Condor was a close friend of Dugu during his later years but when Yeung Gor initially met him/it, no such Dugu-related person was found. Why didn't the condor have Yeung Gor and that person meet? Or did the condor not know any of Dugu's disciples?
An unrelated question, but I think it doesn't hurt putting it here: Does Gwok Jing have any special hero title? Like Yeung Gor's "Divine Condor Hero"?