Cx is the only airline in the world where staff from a subsidiary get on before they do.
I don't know which subsidiary you are referring to as KA is not a subsidiary to CX... owned yes, but not subsidiary.
What do you suppose happens with Qantas, Jetstar, Qlink, VARA, VOZ, Virgin, Lufthansa, Austrian, Brussels, Germanwings, Eurowings, Air Dolomiti, & Swiss to name a few. There are plenty of CX staff bumping KA staff off the popular staff travel destinations like HKT & TPE.