You've adjusted the recipe from 4 (as originally posted) to 4 Servings. The ingredients above reflect 4 Servings, but the instructions reflect the as-posted 4. You may need to adjust the times, temperatures or quantities mentioned in the recipe below as needed.
In a saucepan, cook the sugar and water until the sugar dissolves; transfer to a pitcher and refrigerate until cold. Stir in Grand Marnier, Viognier, mango, peaches and mint. Serve immediately over ice.