Thanks for the advice! And really sorry if I broke the rules. It's my first time to get this kind of fare.
I'm not quite worried about the connecting flight as it's just a 4500 Avios flight by Cathay Dragon - just to secure a seat in advance.
About the seat selection, I have this trip next February and the Business cabin in both my return flight are not that empty - half full for both MNL-HKG sectors and 13/30 for MNL-LHR. I'm not sure if PAL is that popular but I believe there's already someone called and asked for a seat with this fare.
And just for discussion, PAL has sent me their confirmation email with fare details, shown as IT for the Fare (Fare Basis Z9ITPRGB). Does anyone know what's that supposed to mean?