The best/easiest way to get all the miscellaneous hardware is to source them from the same person you are getting the seat from. There is no reason that when removing the seat, they can't remove all the hardware with it. If it is a parted out car, you should get everything with the seats, if it is someone removing the rear seats from their current car you will have to look for the bezel pieces for the back of the 2nd row seats somewhere, as nobody would want to remove those from their car.