Cathay Pacific Asia Miles - Mixed carriers on a Companion flight?

Does anyone know for sure whether or not you can have mixed carriers on a companion redemption ticket? e.g. PVG-HKG-LHR rtn, PVG-HKG on MU and HKG-LHR on CX and VV.

Have called MPO and as usual, get polarised answers from different agents. Better not to call sometimes. :mad:

I'm not sure for other airlines, but in this specific case, for MU+CX, I guess it's most likely no, because MU isn't really allowed at all even for normal "Asia Miles Mixed Carrier awards" ? not to mention about companion...