My niece has a non-refundable ticket that she didn't use issued October 1, 2012.

The ticket is $600 less a $150 change fee.

Can I exchange it for example a $59 Houston-Austin ticket and get an voucher back for $541 dollars that I can use for myself or my nephew?

They are minors and I bought the ticket in case anyone is wondering.

I know I have to pay the $150 fee regardless and it can't be taken out of the exchange any more.

I know AA gives vouchers for the residual that can be used by anyone. Does UA or does the original person have to use the value?

Do the keep the residual as a e-voucher or do they mail a paper voucher to the address on file?