Hi, I traveled in Feb 07 to Disney with a good friend and our two children, who are both 100% tube-fed. When we booked our package through Disney, we were told that we could book the package with dining plan for the two adults and then add the children to the room once we arrived (and purchase seperate MYW park tickets for them). That way the adults could have the dining plan.
However, the cast member told us that we could use their snack and counter service credits if we bought the dining plan for them, and also that their table service credits could be used for dinner shows and character meals that would normally charge an entertainment fee.
For the price of the child's dining plan (something like $12 a day, if I remember correctly), we elected to go ahead and purchase the dining plan. We figured it would pay for itself if we only used the table service credits for the dinner shows etc. as we wouldn't have to pay the entertainment fee.
We went to several character meals and only once were their table service credits used, and we did use 4 of their table service credits for the Aloha Dinner Show. We were able to use their snack credits to purchase orange juice and milk and donuts for breakfasts in our room, and had enough left to buy a few treats for the children back at home that didn't make this trip. We used the extra counter service credits a few times to purchase snacks at Epcot. We did leave with unused table service credits and counter service credits, but still felt the money was not wasted.
It was nice that Disney gave us the option and explained well to us how our credits and the children's (both age 6) credits could be used if the plan was purchased for them.
Hope this helps.
Angela