Under CAO 20.11 (Australian regulations) you are required to carry out training both pratical and theory on the emergency equipment and procedures on each aircraft type for each airline you work for. This training is completed when you first join and then every 12 months. Therefore V Australia cannot make you crew a
VB or PAC Blue flight, as you are employed by V Australia and their AOC is for the B777 only and you are only trained and checked under CAO 20.11 on that type only. In order for you to operate on the B737 or E-JET with
VB or PAC Blue you would need initial training on those types and then a check on each type every 12 months. The same goes with
VB and PAC Blue, the cabin crew from each airline cannot crew the other airlines aircraft.
You will find that V Australia will operate under a fatigue system for duty times. Therefore depending on what time of the day and the length of the sector you do will determine the maximum duty time. BOC flying lowers the length of any duty that you can be rostered for or extend.
Think about it, international flights have a 2 hour sign on and 1/2 to 1 hour (to clear customs) after arrival, so if the flight time is 15 hours (on a good day) from LAX to SYD you duty time from would 17.5 to 18 hours. Then you would need another 30 minute to get from the international to domestic terminal so you are up to 18 to 18.5 hours of duty before you get on the
VB aircraft. The minimum
VB return flight from SYD would be CBR, this flight chock to chock is 90 mins (at best). So the min duty you could do would be 19.5 to 20 hours and 3 sectors (including 1 BOC), no fatigue system would allow this.