As far as I am aware, there is no mechanism that gives Virgin Nigeria pilots a greater chance of employment by Virgin Atlantic than those from any other company, though there may be access to training records etc. which may make things a little easier. I'm not aware of any VK pilots that have made the move to VS - though that doesn't mean it hasn't happened! I have heard that there has been a number of VK FOs that have jumped ship to Far Eastern A340 operators on completion of training, but I can't attest to the truth of this.