I have added an extra day before and not lost my FP+. But maybe just to be sure phone and add the day on the phone and have the CM do it. That's what I did. Good luck!
Our Authorized Disney Vacation Planners are here to provide personalized, expert advice, answer every question, and uncover the best discounts.
Let Dreams Unlimited Travel take care of all the details, so you can sit back, relax, and enjoy a stress-free vacation.