There are several synonyms for the phrase "add sugar to". Some common alternatives include sweeten, sprinkle sugar on, blend with sugar, mix in sugar, and combine sugar with. Additionally, you could use phrases such as enhance with sweetness, add a touch of sweetness, or amplify the flavor with sugar. When looking to substitute sugar for a healthier option, you might use phrases like use honey as a sweetener or substitute maple syrup for sugar. Using synonyms can help to add variety to your writing and make your language more interesting and engaging for your audience.