From my point of view I would suggest that you activate the employee again and then process a pay for the full amount due. If this is a result of retroactive pay it might attract more vacation pay as well.

Once all payments are made you can terminate the employee again and then process an additional ROE for this one pay or amend the ROE issued at termination to include this payment.

If someone has another way to make it simple but using all guidelines please add your comments.

Hope this helps