I guess I don't quite understand here. Are you trying to add a line by purchasing a phone at full retail cost? If so, that is most likely why you don't see anywhere to add the discount.
You can only add the discount to an already existing month-to-month line. Once you have added the line, you would navigate to "Change Features" in your MyVerizon online account. Select the phone which is month-to-month and there should be an option to add the discount.
I am unaware about adding a new line AND the discount at the same time. Whether or not you can do so, I have no idea. I have only added the discount to an existing line after the line became month-to-month. The discount did not automatically add itself after the line became month-to-month, I had to manually add it. I would assume the same with a new line, it won't add automatically but you would have to add it manually. Since you don't already have the line, you can't add the discount before the line is actually in service and would therefore have to do so afterwards, the same way employer discounts are added, afterwards.
