In a large bowl, combine blueberries, raspberries, cherries and 1/4 cup sugar; set aside.
In a large bowl, stir together biscuit mix and nutmeg. Use a pastry blender to cut butter into flour mixture until mixture resembles coarse crumbs. Make a well in the center of the mixture. Add half-and-half all at once. Using a fork, stir just until moistened. Drop dough into 6 mounds on an ungreased baking sheet; flatten each mound with the back of a spoon until about 3/4-inch thick. Lightly sprinkle each mound with additional sugar.
Bake in a 425 degree F oven for 10 to 12 minutes or until golden. Cool on a wire rack for 5 minutes.
Meanwhile, in a chilled medium bowl beat whipping cream, 2 tablespoons sugar, and vanilla with an electric mixer with chilled beaters on medium speed until soft peaks form.
To serve, split warm shortcakes in half horizontally. Using a wide spatula, carefully lift off the top layer. Place bottom layers in 6 shallow dessert dishes. Spoon whipped cream over the bottom layer. Spoon fruit mixture over whipped cream. Carefully replace the top layers. Serve immediately. Makes 6 servings.