P1 seems to be the norm but with Chinese captain as PIC but then again there are not enough foreign pilots to run with 2 on each flight
A PRC carrier a little to the north of GZ that has had foreign based Capts for over 6 years now, has & will not ever crew flights with 2 x foreign Capts. Its a trust issue, most likely an unofficial Caac policy.
There can only be one PIC on a flight- the designated P1. Even the previously rated 330 Capts at CZ have been flying as P2 for 12 months now, non-rated pilots will take significantly longer. As P2 or FO your log book is signed off by the PIC at the end of each flight so no chance you could present this elsewhere as anything other than relief time.
While the contract terms may not be changing, the 'interpretation' of terms will change and you can be sure it will not be to the pilots advantage. This of course is not peculiar to aviation dealings with the Chinese.
Good luck.