For verizon, can I use my Upgrade discount later and use a used old phone temporary

[Ibleachy Mann]

without voiding my-discoun? For instance, I want to get a new smart phone later this year. I don't want to cancel my plan with Verizon. I am also eligible for a discount. Is it possible if I can use my dads old phone temporary and still be eligible for a discount later this summer?