Instead of having a discount on a precise order of a certain aircraft with a certain configuration, it would be nice to be able to create a "global order". The global order would be kind of like adding items in your basket when you go shopping on line. (Except that you usually don't go shopping for billions of dollars)
So, for example, I could order 10 A330-300 with a certain config, add to the basket, 3 A330-300 with an other config, add to the basket, and 7 A350-900. So I would have a total of 20 Aircraft in my basket, and the discount would be for that whole basket of aircraft
This will enable airlines to have a global discount on all the aircraft they buy from an airliner, and there for enable airlines to buy aircraft with diffrent configs. It will also help with the dropping in your credit rating problem when you lease an aircraft.