if the seat is not confirmed

Bonjour Charles, 'confirmed seat' means you paid for it (not just a reservation) and are not on a standby list. It is not necessary to be checked-in and have the exact seat number, if that is what you were wondering...

I had a similar situation (also on a Schengen passport), two separate return tickets with Shanghai in the middle (AKL - PVG - AKL and PVG - AMS - PVG) and applied twice for the 144-visa, on the way to Europe and on the way back to New Zealand) no problem at all.

Counting your hours...

Arriving at Shanghai on the 2nd, so the hour-counter starts the 3rd at 0:00
0:00, 4th --> 24
0:00, 5th --> 48
0:00, 6th --> 72
0:00, 7th --> 96
0:00, 8th --> 120
8:00, 8th --> 128

return:
Arriving at Shanghai on the 14th, so the hour-counter starts the 15th at 0:00
0:00, 16th --> 24
0:00, 17th --> 48
0:00, 18th --> 72
0:00 - 23:59, 19th --> 96 .. 120

so you in both cases under 144

go for it, it is a great opportunity to see a bit of China without all the Visa hassle and in my experience it was handled smoothly and professionally at Pudong. To find the 144 desk, just walk to the complete left (or right, depending on the terminal) at the immigration area just after the temperature-check gate

Thank you very much Sjoerd. Your answer was exactly what I was looking for. Thanks a lot.

Best regards,

Charles