Hi Arlene,
First of all, let me congratulate you on your 45th wedding anniversary! That is amazing, and you are choosing the most fabulous way to celebrate. You're treating your family members to a Disney cruise? They are incredibly lucky to have you.
When you check in at the terminal for your cruise, each stateroom has to have a credit card on file for charging privileges. Someone from each room should put their card on file. That way they will be aware of what they are charging to their accounts. You can then go to Guest Services with them to pull their bills and pay for them with your charge card.
I do have an idea that I like a little better than that. It will make your lives a lot easier. Have them put their own credit card on file for their own rooms. Present them with one Disney Gift Card in the amount of your choice. At the end of the trip, your guests can go to Guest Services and pay for their charges with their Disney Gift Card. This way, you can budget and they can't go overboard with charging privileges. You can order Disney Gift Cards at
www.disneygiftcards.com. Gift cards can be sent directly to your address so you can distribute them personally. If there is a balance left over there is no need to worry. Disney Gift Cards do not have an expiration date and can be used on another trip or even on merchandise at
www.disneystore.com.
I hope this helps. If you have any other questions please let me know. Congratulations again and I hope you have a truly magical sailing! Bon voyage!