Voucher is posted in past payment period and has incorrect invoice date

Good morning,

We had a voucher come over in January and post that has an invoice date of 12/1/2018. The invoice date should have been 12/1/2017. We need to pay these vouchers, however, if we change the scheduled due date we would be paying an invoice before the invoice date. I know you can unpost the voucher to change the invoice date, but the period the voucher was posted in is not open as we are currently in March. Is there any other way to change the invoice date?

Thank you,