Hello Donna!
The current cost to add the deluxe dining to your package is $71.99 for adults and $20.99 for children 3-9 per night. For this price each person gets one refillable mug for the length of your stay and two snack credits and three meal credits a day. The amount of credits you receive will be based on how many nights you are staying at your resort. For example, if you are staying for five nights, each person will get 10 snack credits and 15 meal credits that can be used throughout your vacation.
You can use the credits however you wish. If you want to use four snack credits one day and only one meal credit the next, you can do so. Keep in mind that your credits will expire at midnight on the day you check out from your resort, and there is no refund for unused credits. You can begin using your credits as soon as you check in and receive your Key to the World card.
To answer your question about the Brown Derby, yes it will require you to redeem two meal credits per person. However, the meal plan will cover more than the $71.99 a day. That is just the price you pay for the plan. One of the great things about using the meal plan is that it can end up saving you a lot of money on your meals.
Once you have the plan, you only need to worry about how many credits you have, and not about the dollar amount of your meal. As long as you dine at a restaurant that accepts the plan, you can order whatever you like, even if your daily totals exceed the amount you paid for the plan.
To learn more about what is included with your plan and where it can be used, you can download a copy of the Disney Deluxe Dining Brochure
HERE.
I hope this makes sense and clears up some confusion! Please ask any further questions you may have.