Originally Posted by corporate-wage-slave

It should be a free move, but clearly you are best to wait until ticketed before dashing over to Vueling as soon as the booking is made, I would leave it a few days first. If this is BA codeshared on to VY, booked via BA.com then so long as it shows up in BA.com then you're ok. With Vueling the only time you enter your frequent flyer number (and that would be an Iberia, Aer Lingus or Vueling F number) would be during the Vueling booking system. They have a very stripped down process in VY so it's not got all the bells and whistles of BA.com.