Set the sherbet on the counter about 20 minutes before serving, until it softens enough that a spoon presses in easily but the sherbet still holds its shape.

Scoop the sherbet into a large punch bowl (at least 4-quart capacity) in rough chunks, spacing them out rather than piling them in one spot.

Stir the white grape juice and blue drink mix together in a separate pitcher until the color is even, then pour it over the sherbet chunks.

Stir gently with a ladle for about 15 seconds, just until the color swirls through without fully dissolving the sherbet.

Pour in the lemon-lime soda slowly down the side of the bowl to protect the fizz.

Check the punch is ready: the color should look clear and bright blue, with foam rising and sherbet chunks still visible near the surface.

Garnish with blueberries and lemon wheels, then ladle into cups immediately so the fizz is still active when it reaches the table.