it depends on the dates and times of travel and when you buy the tkt. as for the child discount DL requires that you call them about it directly but you can use their websight to book yours and then call them give them your ressie info and then they can book the under 2 child for you and then cross reference the reservations so that they know the child is traveling with you. this is what I had to do when I couldn't get it to work for me on their sight. they were great about it!