I am facing an issue with the discount calculation.
There are three coupon which are applied automatically without coupon code (coupon 3, coupon 4, coupon 5) and one more coupon code which i have added manually(ONEFREEGIFT).
Coupon 3, coupon 4 and coupon 5 has the discount amount $6, $8, $10 respectively and ONEFREEGIFT has $149 (As we are using Amasty promotion so there is one promotional item added in the cart and its price consider as discount amount)
Case #1 (Discount not working):
Please check this screenshot, 
Discount should apply $149 instead of $147. As promotional item has the $149 amount. In the sales rule configuration, The priority is same for all rules (Priority is 0 for all rules).
Case #2 (Discount working fine):
Please check this screenshot, https://www.awesomescreenshot.com/image/37927045?key=1a8f4cd5fea5f3f79fadc32b06aa605a
Discount is working fine for ‘ONEFREEGIFT’ coupon because i have set the priority from the admin for each rules. ONEFREEGIFT, Coupon3, coupon4 and coupon5 has the 0,1,2,3 priority respectively.
Note: If i set the priority then only discount amount working fine. But i don’t want to set the priority for each rules as there are more than 500 rules. So i can not change it manually.
So, How can i fix this discount amount issue without setting the priority.
Thanks,