Montana makes a good point. While we are all required to leave the bar while a line up is on, we do not have to stand in the line up if we have a customer waiting for us in the bar.
But if the lady is unsure of your intentions to party soon she might not make you a priority or might not know to go back to you after. So it is best to tell the lady you want a party and ask her not to stand in the line up.