Change Vendor Name on Invoice?

I have a Purchase Order for inventory that I need to bill.  It was already paid by personal credit card by an employee.  I need to reimburse the employee, not pay the vendor on the invoice that will generate when I bill the PO.  I don’t want to show the employee as the PO vendor because that’s just not accurate. 

Is it possible to change the vendor name on the invoice when it generates so the employee gets paid instead?  Or, will NS tell me that the invoice is connected to other documents and I can’t change the name?  (I’m leery to try anything I might not be able to fix once I get started - or that leaves a long messy trail of corrections.)