Originally Posted by
caipiroska
As described in other threads you can "Online Check-in is available 23 hours prior to the departure time of your transfer flight"
This means not 23h before the flight leaves PVG, but before your second leg flight departs.
actually, this is meant for the case where the transfer is the first leg...
it's usually 23 hours prior the first leg and you can check in all subsequent legs then.