In a large mixing bowl, combine the defrosted and chopped frozen cherries, finely minced fresh cranberries, and well-drained crushed pineapple. Sprinkle in the sugar and toss gently. Allow this blend to sit at room temperature for about 30 minutes.

After 30 minutes, carefully drain any excess liquid from the fruit mixture using a fine mesh sieve or colander.

Gently fold in the roughly chopped pecans and mini marshmallows into the drained fruit mixture.

Carefully add the whipped cream to the fruit and marshmallow mixture, folding gently until combined.

Serve immediately or refrigerate for up to six hours before serving.