If you use the GAD voucher for park admission, you can upgrade it to a one-day hopper for 55.38 per person. If you use the voucher for the FP exchange cards, they are valid only at the park issued on the date issued.
I agree that it's not the best use of a GAD voucher. Like I said, we have 7 vouchers, and we'll have 7 park days, so we are using them for FP's EVERyday we are there.....I am soo excited!!