Blueberry-Peach Shortcakes

Preheat oven to 425 degrees F. In cup, mix lemon juice and cornstarch until smooth. In 3-quart saucepan, heat blueberries, 2/3 cup sugar, and lemon-juice mixture to boiling over medium-high heat. Reduce heat to medium; cook 1 minute. Stir in peaches; set aside. Prepare biscuits: In large bowl, mix flour, baking powder, salt, and 1/3 cup sugar. With pastry blender or two knives used scissor-fashion, cut in 9 tablespoons cold margarine or butter until mixture resembles coarse crumbs. Stir in milk; quickly mix just until mixture forms a soft dough that leaves side of bowl. Turn dough onto lightly floured surface; knead 6 to 8 strokes to mix thoroughly. With lightly floured hands, pat dough 1 inch thick. With floured 3-inch round biscuit cutter, cut out shortcakes. With pancake turner, place shortcakes, 1 inch apart, on ungreased large cookie sheet. Press trimmings together: cut as above to make 8 shortcakes in all. With pastry brush, brush shortcakes with 1 tablespoon melted margarine or butter and sprinkle with 1 tablespoon sugar. Bake 15 to 20 minutes until golden. Beat cream with 2 tablespoons sugar until soft peaks form. With fork, split warm shortcakes horizontally in half. Spoon some blueberry-peach mixture into each split shortcake; top with sweetened whipped cream, then some more blueberry-peach mixture.