This will make about 4 1/2-quarts of soda.
1 can (12-oz) frozen, pulp-free orange juice concentrate, thawed - do not dilute
2 bottles (2-liters each) lemon-lime soft drink, chilled
1 to 2 oranges, thinly sliced
When ready to serve, stir together the orange juice concentrate and the lemon-lime soft drink. Serve over ice in individual glasses, garnished with an orange slice.