Rumour. I saw the pics.
First they put the Brit pic inside her car wearing something like a white wedding dress. only her top that is seen. But then after then, someone posted another image when she's out of the car. and no, she's wearing like a baggy white long jumper.
However, I do think they're having rehearsal because Lynne and Jamie Lynne were there. On the second thought, I don't know.