At&t two year contract?

igot an at&t two year contract two years ago. then a few months later iadded two lines, a total of three. so for the first phone it's already two years but for the other two it's not. iwant too switch to verizon alreadyy can ido that now or do ihavve to wait till the other two phones complete the two years too since it's a familyy plan. thankk you((: