Are you using an affiliate program that uses a coupon/promo code to identify the user? And your sale is also using a promo code? If so, check out the Shopify manual on combining discounts.
If you’re using a link-based affiliate program, like ours, you should be able to attribute the sale to the affiliate and the customer should be able to use whatever coupon/promo code they want. This would allow them to use a sales discount code shown on your site or one provided by the affiliate, whichever is greater. The affiliate would get credit for the sale no matter what.
If you’re a retailer in the kids/parenting/family category, happy to chat more about Audenticity and see if it’s a good fit.