Each and every person of the family gets a visa on his/her own passport including the principle applicant ...it's necessary that the principle applicant land with the family or land 1st ..but even the rest of the family have to land prior the expiry of the visa in their passports.
as an example: [size=14pt][size=14pt][size=14pt]if you are the Principle applicant and you have a wife and 2 kids, the 4 of you will get visas stamped on the 4 passports with the same expiry date (lets say dec 31, 2014)...you should land with them before that date ,or land alone before that (lets say sep 1 2014) without them,but then they all have to land before or on dec 31,2014 before their visas expire[/size][/size][/size]