Welcome aboard, Helen! What a wonderful treat you are giving your family! The gift of time spent together on a Disney Cruise Line vacation is truly priceless. My family and I have traveled with extended family on Disney's ships and these have been some of the best vacations we've had, as it's so much more fun to experience the magic of sailing with Disney with so many more family members!
Gratuities are customarily paid per person, including children, and are traditionally as follows:
Stateroom Host: $4/night, per person
Server: $4/night, per person
Assistant Server: $3/night, per person
Head Server: $1/night, per person
You'll find that the Cast Members go out of their way to make this experience absolutely incredible, especially for the children, so my family and I usually add a bit extra to their gratuities before we disembark. Gratuities can be pre-paid before you set sail, which really helps budget and it's always nice to know that there is one less thing to take care of onboard.
I hope those details help as you plan this amazing family trip, Helen! Please stop back as you continue to plan and let me know if I can help with any other questions! Happy cruising!