I found this recipe a while back on allrecipes.com.
Super easy and yummy margaritas.
2 (12 fluid ounce) cans frozen limeade concentrate
1 liter artificially sweetened citrus soda
12 fluid ounces tequila
Empty the limeade into a 2 quart pitcher. Using the empty limeade cans, fill each one twice with citrus soda and pour into the pitcher. Fill one limeade can with tequila (I fill it mostly with tequila and top it off with some Triple Sec) and pour into the pitcher. Adjust alcohol to personal taste. Mix well and serve.