The whole 28 oz package of Betty Crocker® Potato Buds® mashed potatoes (dry) makes 32 to 34 servings : for that amount you need 13 1/2 cups of water, 1 cup margarine or butter, 1 tablespoon plus a teaspoon of salt and 2 1/2 cups milk. I would advice you to do 2 boxes or 1 box and 2 times the servings for 7 servings.
As far as the rest of the ingredients for 50 you will need about:
3 1/2 cups shredded cheddar
6 cups bite size crackers
about 3/4 cup chives.
Answered 04/17/2013 by aamione