I have used Delta miles to book a business class ticket to Australia. The flight is LAX-SYD-LAX-JFK. Is it possible to change the date of the outbound flight without cost? Also, there were no available flights from JFK to LAX at the low level when I booked initially. If a flight were to open up at the low level, would I be able to add it to my ticket? Thanks for any advice. By the way, the trip begins at the end of June. Looking to move the outbound to mid June. LAX-SYD-LAX is on V Australia. Thanks.