When I offer a Custom Discount promotion, will it also include the discounts already in my settings? For example, if I want to offer 15% discount for Feb 1-14 but also have standard discounts for 7 days or more, will it combine the 2 discounts?
Yes, it will. It is always a good idea to view your listing as a guest after you make a calendar adjustment (price +/-, discount, etc.) to see if the change is doing exactly what you want it to do.