Why would they do that? I mean, what if your phone break and you want to switch the phone? If it doesn't work, they will end up with a pissed customer and lost money.
I just got a family plan for 4, unlimited minutes on the first two lines (women in the family), and 500 per line for remaining two, unlimited text, and 200 Mb of data on each line for $130. I think that is pretty good. I did have to go from month to month to their 2 year contract. No changeover fees, perhaps because I was month to month