I'm on a family plan of 4 phones. Only my phone has a data plan (unlimited). However, my phone is not eligible for an upgrade until 2/25/11. The 3 other phones are eligible for upgrades. I'm trying to upgrade one of the 3 eligible phones so I can get the subsidized price, however, on apple.com, it's asking me to choose a data plan when pre-ordering. Is there a way to keep the my unlimited data plan while upgrading one of the other 3 eligible phones to take advantage of the subsidized price? Big thanks.