Fill a tall glass or mason jar with ice. Pour 2 ounces orange juice, 2 ounces pineapple juice, 2 ounces sweet & sour mix, 2 ounces silver rum, and 1 ounce amaretto into the glass. Stir to combine.
Pour in 1 ounce grenadine slowly so it falls to the bottom of the glass. Then top off the cocktail with a splash of lemon-lime soda.
Garnish with a Maraschino cherry and an orange slice on a toothpick. Serve immediately.
Notes
For a 1 gallon batch (12 servings):
3 cups orange juice
3 cups pineapple juice
3 cups sweet & sour mix
3 cups silver rum
1½ cups amaretto
1½ cups grenadine
Lemon-lime soda, to top each glass when serving
Maraschino cherries and orange slices, for garnish