this is one of those things, ask 5 different people get 5 diff answers. i had a single line with iphone and the grand fathered unlim DP. added a second line and got a samsung galaxy s2 (SGS2). this has the 2GB DP. if i get rid of the 2nd line, ands swap out/ use whatever word you want, do i lose the grand father plan.. i asked over at the android forums two people say no. asked two friends one says no the other says yes.