I and my wife have a valid us tourist visa,my married daughter and their daughters aged 9yrs and one and a half year also have a us tourist visa ,my son is on h1b visa at LA-US.and we intend to visit our son during April 2010, my daughter wish that we take their daughters to us along with us.(I my wife and my two grand children). Is it allowed to travel to US with children not acompanied their parents?,or do we have to carry any aditional documents? plase reply.