Sure, you can add additional flavor to a premixed
juice. The problem might be finding the one that the vendor is using. There's 3 major brands of flavor and although they may have the same name, they don't necessarily taste the same. In fact some are quite different. Once you figured that part out it most likely would be just a matter of putting an additional 5 to 10% in there. It would also lower your nic level though.
Most vendors will work with you, and if you put a note in the comments of your order they will probably accommodate your request for extra flavor even if it's not listed on their site. The best thing would probably be to ask before placing your next order. It would save you the hassle of figuring things out and doing it yourself if they will do it for you.
