Drain both cans of lychees, reserving 1/2 cup of the syrup. Take each lychee and carefully stuff with one blackberry each. In a large punch bowl, mix together vodka, tart cherry juice, and orange juice, and refrigerate until chilled. When ready to serve, add the stuffed lychees and top with club soda or ginger ale for a sweeter drink. Makes about 12 servings.