Reinstate should only be used if you have casual employees that work infrequently and they are currently inactive but you want to pay them for a number of pays. It is not recommended to use this if you are wanting to add back a permanent employee that has been paid a final pay.
You can pay inactive employees without reinstating.
If you want to pay an inactive casual employee for the extra hours they worked for you at short notice.
If you processed a final pay and then need to pay extra hours, you can add them to a pay and process the final pay, which in most cases will add the holiday pay required on the payment.
If you have an inactive permanent employee that is doing some short term casual work for you.