Heat oven to 350°F. Lightly spray bottoms of 2 (10-inch) round and 2 (8-inch) round cake pans with no-stick cooking spray; set aside.
Beat egg whites at high speed in bowl, scraping bowl often, until soft peaks form. Continue beating, gradually adding 1 1/3 cups sugar, until stiff peaks form. Set aside.
Combine remaining 2 cups sugar, cake flour, baking powder and salt in another bowl; mix well. Stir in 3 cups water and all remaining cake ingredients. Beat at low speed, scraping bowl often, until smooth. Pour batter into 8-quart bowl; gently stir in egg whites. Gradually and gently, stir in remaining 1 cup water.
Pour about 6 cups batter into each 10-inch prepared pan and about 4 cups batter into each 8-inch prepared pan. Tap pans on counter top 2 to 3 times to remove air bubbles from batter. Bake 25-30 minutes or until cake pulls away from sides of pan. (If necessary, rotate pans in oven for even browning.)
Let cakes stand 10 minutes; remove from pans. Brush all browned crumbs from surfaces of cake with fingertips. Cool completely on cooling racks. Decorate or wrap tightly in plastic food wrap; freeze up to 5 days.
Soften gelatin in bowl in 3 tablespoons water. Stir together softened gelatin and all remaining glaze ingredients in 1-quart saucepan. Cook over medium-high heat 3-4 minutes or until gelatin is dissolved. Refrigerate, stirring occasionally, 30-60 minutes or until gelatin mounds with a spoon.
Beat shortening and butter in bowl at low speed, scraping bowl often, until well mixed. Continue beating, gradually adding powdered sugar alternately with lemon juice and 2 tablespoons lemon zest, until fluffy. Add 1 to 2 tablespoons milk, if necessary, to reach desired spreading consistency.
Place 1 (10-inch) layer on 10-inch cake cardboard round, bottom-side up. Spread with thin, smooth layer of frosting; top with thin layer of raspberry glaze to within 1/2-inch of edge of cake. Refrigerate 30 minutes or until slightly set.
Place 1 (8-inch) layer on 8-inch cake cardboard round, bottom-side up. Spread with thin, smooth layer of frosting; top with thin layer of raspberry glaze. Refrigerate 30 minutes or until set.
Place remaining cake layers, top-side up, on matching bottom layer. Frost sides and top of each cake. Spread so frosting is smooth. (If necessary, dip metal spatula into water, spread over cake to smooth frosting.)
Spoon frosting into pastry bag with ribbon decorating tip; pipe 1/2-inch ribbons around outer edge of 8-inch cake and across top of cake to form decorative lines. Change decorating tip; pipe tiny dots or “V” design on decorative ribbons.
Place 10-inch cake onto large platter or tiered cake stand. Center 8-inch cake on top of 10-inch cake. Decorate with frosting, as desired. Place fresh cut flowers on top and around cake, if desired.