I fly in and out of PVG weekly, and I'm in MNL at least once a month also. I'm OW Emerald, but I'm usually flying on an economy basic ticket.

I don't think I've ever had an occasion on which CX check in desk at MNL has refused to move me to an earlier flight. No fuss whatsoever. I think they like to let passengers 'fly forward' as much as possible on account of the general .... -how that is NAIA.

On my weekly PVG commute, the check-in desk is generally happy to let me move onto an earlier flight, however the lounge agents have never been able to do so, advising that I would need to go back through immigration to the front desk. This might be a regulatory thing. I usually just commiserate in the (nice, by China standards) CX lounge and wait to get on my ticketed flight.