Create a promotion with override stacking

Use Case: Creating a promotion that can stack on top of other non-stackable promotions.

Given there are some promotions with higher priority and are non-stackable, and the merchant wants to create a lower priority shipping promotion to stack on top of the non-stackable promotions. In this case, we have 3 promotions in the store:

promotion	priority	stackable	override_stacking
cart discount tier 1 (less than $100)	100	false	false
cart discount tier 2 (more than $100)	90	false	false
free shipping		false	true

To set this up in the Promotions Builder:

1. In Commerce Manager, go to Merchandise > Promotions > Builder. Edit or create a new promotion.
2. On Promotion Builder editing page, under the Advanced settings, toggle the override-stacking flag to ON.
3. Create the desired conditions and actions for the promotion.
4. Save all the changes.
5. Setup promotion code if the promotion has Coupon-driven toggle ON (by default). See Creating promotion codes.

See detail Commerce Manager steps.

Result: The promotion cart discount tier 1 applies to the cart first since it has higher priority, while the promotion cart discount tier 2 is not applicable since it has lower priority and first promotion is non-stackable. The free shipping promotion can be applied on top of promotion cart discount tier 1 because it has the override_stacking set to ON.