This is much better than Mainbrace, in my opinion (another gin / pink grapefruit drink). It enhances all of the natural features of the grapefruit - campari for the colour and bitterness, lime for the acid, and syrup for the sweetness.
To me the only purpose of this drink would be to sneak alcohol into your child. Double the rum, swap the syrup for amaretto, add saline and more bitters.