In a 4-cup measure, add the red wine, mango nectar, and brandy. Stir to combine.
Blend the lime juice, superfine sugar, tequila, Triple Sec, and ice together in a blender until smooth. You may need to add more ice to make is slushy. Moisten the rim of a glass and coat with salt, then pour in the frozen margarita. Pour Sangria into the center of the margarita glass and swirl. Repeat with remaining ingredients and glasses.