I e-mailed carnival about this as my children have a different surname and they informed me I only needed the childrens passport, so thats all I am taking, but I am also travelling with Princess and they want new marriage cert! childrens passport! and a letter from my ex! Have got him to sign just a brief letter stating it is ok for them to travel with me. I wonder if he was taking them if all this would be required, I think not.
Anyway hope this helps bye for now