There isn't anything you can do in the Square app specifically. What I would recommend is keeping good documentation of the process. Document the Square Transaction number in question and a picture or copy of the receipt, The item or amount being refunded, the check number with a picture of it, the day it was given or mailed to the customer, the day it was cashed. Have the customer sign a short form stating that they are aware they are receiving a check back for a credit card purchase and a copy of their driver's license.
