Hm, according to our email records, we have replied to 3 emails from you within the past 2 weeks. We cannot tell why you did not see those responses; once a message leaves our server, its routing from that point on is out of our hands.
You can create a discount code that the buyer could give to their friend to purchase another copy of your eBook, and perhaps offer that code as an "online coupon" in your thank-you page or email:
If you wanted the PDF Stamp to identify the friend rather than the original buyer, that friend would need to order the eBook themselves, since the name and email on the stamp is taken from the PayPal account details of the actual buyer of the file being stamped. If you provide a purchase link on the thank-you/download page for the original buyer to purchase an additional copy at a discount for their friend right away, that buyer's info would be stamped on the extra copy, rather than their friend's info, although the stamp would show a different Transaction ID.
You might also consider whether the buyer might resent being offered a discount to buy a copy for a friend when they didn't get a discount on their own, original purchase.
You can use our Updates feature to send previous buyers free download links for the latest edition of a product file:
However, such Update links would not be able to stamp their downloads, since there is no checkout being performed to provide order data that would be stamped to the file. If you want to offer a free update that issues stamped files, you would need to create a discount code for the full price of the item, then send that code or a direct purchase link incorporating the code, which they would use to order a new copy of the product for free using our Free Checkout, and that would be able to provide checkout data to be stamped to the file.
Affiliate share commissions are calculated on the full price the buyer actually paid for the item, before PayPal takes their transaction fee out of the buyer's payment.