And under the UK system you are definitely not allowed to carry anybody either.
We're talking about the CPL QXC, on a modular course here, right? So the assumption is that the PIC already has a PPL and is thus licensed (and current) to carry passengers? My understanding is that in that case you are allowed to carry passengers on the CPL QXC. If you have any supporting documentation to the contrary, I'd like to see it.
Obviously, on an integrated course you never gain a PPL as an intermediate step. So until you pass the CPL test, you're not legal to carry passengers and act as PIC at the same time. So you're either flying solo or with an instructor on board.
also the FAA CPL X/C requires three landings, not two.
This is getting interesting. I can't find JAR-FCL right now, but I think their phrase is "two landings at an aerodrome different from the aerodrome of departure" or something like that. That would mean that an A-B-C flight would qualify. The a. ii. phrase I quoted from LASORS used the same phraseology, but the (*) note from LASORS talks about "two intermediate
aerodromes", suggesting that an A-B-C flight is not acceptable, but an A-B-C-D or A-B-C-A flight is.
Whopity, is your quote from ICAO or from the Singaporese ANO? Because that quote also seems to support that an A-B-C flight is acceptable.
And of course if the FAA requires three landings, then an A-B-C flight would not be acceptable either. Unless you do a stop-and-go in addition to a full-stop at either B or C, maybe?