Bookinglayer provides you different discount options, which you can see here.
You can manage the discounts within a package by
1. Clicking on the Inventory Module
2. Clicking on the Packages section
3. Select or create a package
4. Within the package, click on the Discounts section. Here you can see all the discounts that apply to this package.
5. If you want to add a new discount, click on Manage Discounts
6. See this article how to add a discount to a package or create a new one.