While I agree with Dave, I also understand the financial aspect of this to you. I assume you are traveling with your husband and kids (one of which is adopted??). I don't know what the travel rules would say but if you and you husband had a passport and you had to fly back home in the middle of the trip, would the kid's birth certificates allow them to fly with you??
Again, I'm not sure. For that matter I don't know how the situation would be handled if you didn't have a passport and cruised in and flew out now..
But my way at least allows you to defer 3/5ths of the expense unitl the next time you leave the country.
Just a thought. And I would suggest looking into this in more detail as I'm only guessing.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007