Pour white cranberry juice, pineapple juice, orange juice, coconut rum, and white rum into a large pitcher.
Stir together with a long spoon.
Add coconut milk or coconut cream and mix.
Stir in simple syrup if desired.
Pour in lemon lime soda just before serving.
Drizzle grenadine over the top for color and flavor.
Fill glasses with crushed ice and pour punch over. Stir gently before serving.
Notes
Adjust creaminess with more or less coconut cream. Use mango juice instead of pineapple for a fruity variation. Keep punch over ice if serving outdoors.