Use a large bowl to combine all ingredients.
I recommend mixing all canned fruits first. Dump fruit into bowl with juices. (If any of your fruit is in light syrup, strain off the syrup)
Then stir in the sour cream until completely dissolved, if adding in Grand Marnier do so at the point as well.
Fold in marshmallows and your fresh grapes. This is also where you would add your optional coconut flakes.
Cover bowl and chill overnight in the refrigerator stirring occasional to breakdown the marshmallows into juice.