Hi, @olukairetail
At this time, it would not be possible to reintroduce the order numbers back into the POS receipts. I would be happy to pass this feedback up to our development team on your behalf.
In the meantime, have you checked with the developer of your returns app to see if their app has a way to pull up orders via the receipt number? In our Shopify orders admin, entering the receipt number will populate the appropriate order (and its order number) at the end of the search.