As noted before, I only have one phone on my plan atm, I'm worried that adding a new one will change my plan to a Family Share Plan and screw with my Unlimited data.
Adding a line to an individual nationwide account changes it to a nationwide family share plan, but that does not screw with your unlimited. What screws with your unlimited is changing your plan to a share everything plan. A nationwide family share plan is not the same thing as a share everything plan.
So basically the question I have is how, if possible, I can upgrade my phone while keeping my unlimited data instead of having to buy a new phone at full price.
If you use the unlimited data line's upgrade on your unlimited data line and then activate the new subsidized phone on your unlimited data line, you will be switched to a 2GB data plan. Period. The only reason those of us who have a family plan can get away with keeping unlimited data is because we are not using the unlimited data line's upgrade on the unlimited data line. We are transferring it to a line that doesn't have unlimited data and purchasing/activating the new subsidized phone on that line without unlimited data.
As I stated above, if you use your unlimited data line's upgrade on your unlimited data line and activate the new subsidized phone on your unlimited data line, you will be switched to a 2GB data plan and the only hope you have is to convince a rep to switch you back to unlimited data within 14 days or reverse the upgrade by returning the phone within 14 days. Some have been able to convince reps to switch them back to unlimited data when they upgraded through bestbuy.com online because when you upgrade through bestbuy.com, although it tells you that you will lose unlimited, you can continue through the checkout process without actually selecting a new plan and your invoice will say keep current plan.
However, when you go to activate your new phone purchased at bestbuy.com on your unlimited data line, you will be switched to the 2GB plan. You then have to argue to be switched back to unlimited data since you never selected the 2GB plan. Some reps will do it, some won't. You have 14 days to get this accomplished. If you can't, then you need to reverse the upgrade by returning the phone to best buy to get your unlimited data back before the 14 days is over. It doesn't matter that best buy has a 30 day return period for the phone. Your contract is locked at 14 days so if you return the phone 15-30 days after you purchased it, you will get your money back from best buy but you will have forever lost your unlimited data without any hope of getting it back.
You can add a line to your current individual plan and this will convert it to a family share plan and you will not lose unlimited data on your original line. However, if you have unlimited texting and want to keep it, that added line will likely not be cost effective even if you sell the 2nd subsidized phone to recoup some of the costs of the new line.
If you can give up unlimited texts or live with 700 voice minutes, there might be a way to make it cost effective to add a line assuming you are going to sell the 2nd subsidized phone to recoup the costs of the added line.
What is your current individual plan and how many minutes and texts do you need per month?