I've always received a credit (minus a $5 pp phone service charge) when the fare has gone down. If you are leaving soon, you may want to take it now. If you're not leaving for a while, you might consider waiting to see if the fare goes down even further. You can only get the fare difference credited once. So only you can decide if you want to gamble or settle for the $20 credit. As far as putting it toward your niece and nephew's tickets, the way I understand it is that if you booked all 4 tickets through your account the credit would come back to you and then you could use it toward the others' tickets. If you didn't use an A+ account number I think the credit goes to individual passengers. I'm really not sure on tickets booked outside an account. Your best bet would be to ask when you call for the credit.