Cranberry Elderflower Champagne Punch cocktail

Ingredients

• 3/4 cup elderflower liqueur ​(​St. Germain)
• 1 1/2 cups cranberry juice
• 1/2 cup Simple syrup 
• 1/2 cup Lemon juice 
• 1 (750 ml) bottle sparkling wine
• 1 1/2 cup club soda
• Garnish: cranberries, seasonal fruit, or citrus slices