OK, i understand. My solution would be to change the main category of the products to SALE. But, on my website, i have added a custom function that sorts the products by SKU. From your explanation i understand that default prev/next order is the order in which the products have been added. So i need to change the prev/next order to also be by SKU. Can you help me with this? Or, at least, point me to the theme file and code lines that implement the order of the prev/next , so i can customize it myself?
Thank you!