Gift Vouchers in Multi-Vendor

How do Gift Vouchers work in Multi-Vendor? That is, if Admin creates a gift voucher for someone to use in the store, who ‘pays’ for it? This is the scenario: We want to create a gift voucher that a customer can use to purchase products from any vendor. When the customer uses the voucher to ‘pay’, does the vendor receive their usual amount of money, but we (as Admin) pay for it? If so, how does this get set up? I can’t find any instructions for this for version 4. Thanks!