Fill a large pitcher with the ice, orange slices, lime slices, and cucumber.
Pour in the grenadine, lime juice, bitters, lemon-lime soda, orange soda, and sparkling water if using. Stir gently once to combine without flattening the bubbles.
Serve:
Divide the Chapman among four tall glasses and add a maraschino cherry to each.
Serve immediately while cold and fizzy.
Notes
For a sweeter drink, add another splash of grenadine; for a sharper drink, add more lime juice.
Use alcohol-free bitters if you need the drink to be strictly zero-proof.