There's nothing like a bubbly, homemade cocktail.
In medium saucepan, simmer citrus juices, sugar, and 2 oz. water over medium, stirring often, until sugar dissolves, about 3 minutes. Let syrup cool. Fill pitcher about halfway with ice. Stir in syrup, gin, elderflower liqueur, and Campari. Strain into 8 coupe glasses. Top with rosé. Garnish with grapefruit twists.