There are 2 discount types: product discount and order discount.
1. Product discount: Selly sale, upSale, bundle, wholesale offer and Shopify discount "applies to specific products or collections".
2. Order discount: Selly motivator offer and Shopify order discount.
3. Discount combination:
If discounts are the same type, the highest discount is applied.
If discounts are NOT the same type, product discounts are calculated before order discounts.
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Below are some practical examples about a cart contains product A $100 and product B $200:
1. Selly discount 10% for product A, Shopify discount code 10% for product B.
=> 2 discounts are applied normally: A $90, B $180, cart $270.
2. Selly discount 10% for product A, Shopify discount code 20% for product A.
=> The higher discount 20% is applied to A: A $80, B $200, cart $280.
If you want to offer customers 10 + 20 = 30% => you can set the discount value of the code to 30% instead.
3. Selly discount 10% for product A, Shopify order discount code 10%.
=> 2 discounts are applied normally: A $90, B $200, cart 290 * 90% = $261