Thank you for reporting these sightings from northeast China. I knew about the resightings of L9 already. Both L8 and L9 were flagged on the same night, 22 March 2012. L9 was seen in Hong Kong until 31 March, and then in Liaoning from 6-11 May. L8 was seen in Hong Kong until 28 April, but this report is the first sighting since then. L8 is a first-summer bird, which may explain why it has not continued further north to breed.
A shame that you were unable to read the engraved flag on the bird at Shuangtaizi, but thank you for the sighting, at another site on the Yellow Sea. These results show the importance of the Yellow Sea as a stopover for birds from Hong Kong - all resightings of Hong Kong-flagged Grey Plover have come from the Yellow Sea, mostly from Liaoning.