since you are her parents you aren't divorced ( i assume) and you are all traveling together you should not run into any kind of problem. If there is any kind of form that needs to be signed when you embark the ship, the both of you will be present to sign it. In regards to the excursions, if your daughter goes with the grandparents and you and your hubby go on another excursion it might not be a bad idea to have a signed form for consent for medical treatment, all you need is to simply write up something saying that you give your parents (names) permission to have medical treatment for your daughter(her name) from date to date, sign it, have your parents sign it and then get it notarized