I have a one VDB voucher for $300.
If I buy a $120 ticket, I have the option to make that ticket a 'Flex' ticket, which will allow me to change it without fee. "Upgrading" to a 'Flex' ticket will cost me near $300 total. So at this point, I can use my VDB.

If I "cancel" that Flex ticket, what happens? Does it deposit back the money into my VDB voucher, or does it create a brand new voucher? If that's the latter, can that brand new voucher be combined with another VDB?