Use different device on line with Promo credit

[yakovk26]

Hi there!

I have a line/phone that is on a payment plan with a (trade-in) promo (let's call it line-1),
I have a second line that does not have any payment plan on it, (line-2) 

I want to buy a new phone (also with a trade-in promo) and use it with line-1...
I suppose I could buy it on line-2 (which doesn't have any payment plan), and just use it for line-1, but I'm not sure what would happen to line-1's payment plan (and promo credits) when I change the phone.

To clarify, I'm not planning on stopping to pay line 1, as I still have 14 months till the device is paid off, I would just change the device used on that line...

Also, If it is possible to do that (meaning I can buy the phone on line-2, use it on line-1, and stay with both trade-in promotion credits) would it also be possible to use the old line-1 phone on a completely different plan...?

My apologies if such a question has already been asked or if this is a dumb question, I tried searching, and I could not find an answer.

Also, I'm not sure it belongs in this location (BYOD) - but I couldn't find one for Trade-In promotions so I figured this is closest to it.

Thanks in advance to anyone that can help me out here.

[vzw_customer_support]

Yakovk26, getting a new phone is very exciting and I can understand having questions when planning that change. Let's first start by checking exactly which promotion you are looking at as most promotions these days do require the trade in. -Loren

[yakovk26]

Hi!

Thanks for replying, 

Honestly, I tried explaining my question as best as I can so no more information should be needed, but I guess if you answered and still have a question, I'll try to provide more information. 

Both promotions I'm talking about are trade-in promotions, 
line-1 I bought almost a year ago, and the promotion credit (payment plan) is for another 14 months...
line-2 doesn't have any promotion or payment plan on it... it's my own phone.

Now:
My goal here is to buy a new phone with "another" trade-in promotion, (I will be trading in a completely different phone)... 
The issue is that I actually want that phone for line-1 (my wife) not for me.
I don't mind the payment plan being on line-2... but the phone will not be used on that line.

So what would happen is that I would be buying a phone on line-2 with a 36-month trade-in promotion, but I would use the phone on line-1... 
That in itself (using on a different line) is not an issue according to my google searches and other posts,
the issue is that line-1 already has a payment plan with a promotion connected to it, and if I change the phone I'm not sure what would happen, 

In my understanding these are the 2 possibilities:

1. Being that I have 2 lines with a payment plan on each, Verizon wouldn't care that I'm using different phones... or
2. Because I switched line-1's phone, and I'm not using the phone I got a year ago... that promotion will be lost, and I will have to pay the rest of the phone in full.

P.S.
Honestly, I was hoping for a user who has already experienced this to answer, not Verizon agents, as it has been my experience that Verizon Customer Service doesn't always know what they're talking about, 
I'm really not trying to be mean or upset, I understand there is so much info and 1 person can't possibly know everything, the issue is that I have already lost over $1000 by different agents telling me wrong information, so I just hoped that someone has already done this, and would be able to answer me...

[vzw_customer_support]

We appreciate those details! We would like to take a closer look into your account. To continue, please send a Private Note, thank you!

-Jordan