When using Bundles Bear, you can not apply other discounts from other apps / manual discount codes.
We apply discounts by dynamically generating a discount code.
That unique discount code is added to the order once customers proceed to checkout.
As I'm sure you are aware - Shopify does not support multiple discount codes per a single order.
If customers manually enter another discount code - it will replace the pre-generated one.
If you are using other apps that apply the same tactic - one of the discounts will not apply.