A large portion of Second Officers in Cathay are married, and i doubt they would look favourably on people who are single (they'll take whoever they can get at the moment
). Cathay use to provide tickets for wives to come to HK when you're being interviewed as they are aware that the wife must also be happy and onside with the move here. Should you be accepted into CX they will have to process the paper work for you, wife, and child to get visas, and organise medical cover etc etc etc. So really it is logical to get all the information at one time rather than doubling up on it.