I am considering adding a "free one way" from PHL-DFW in April (I am DFW based and need to get to/from PHL) for a China trip. My award trip that I was going to add it to is to Australia in Oct/Nov. I have a business class routing on Cathay Pacific through Hong Hong on hold (no business/first class on Qantas more direct flight.) Is there a downside that I am missing to doing this? i.e., does it prevent changes after my April leg is flown in April? I am AA EXP.