I am booking an AA flight through the Citi TY Portal for the first time and see that there is an option to pay for part of the flight with cash instead. Is it possible to book the flight using a combo of TY points and my Citi AA Plat card in order to get the free checked bag benefit. Is there a minimum threshold I have to put on the Citi AA Plat in order to trigger the free bag? Or does it not work at all if I am purchasing via the TY Portal? Thanks!