Place 4 mermaid cupcake liners in a muffin tin. Scoop one scoop of vanilla ice cream. Freeze.
Using the candy melts and mermaid tail molds, make 6 - 10 tails. Allow to set and store until ready to use.
In a chilled blow using a chilled beater, whip 1/2 cup heavy cream with 6 tablespoons confectioners' sugar to stiff peaks, adding blue food coloring, just a drop or two for desired color, after a few seconds. Refrigerate after you achieve stiff peaks.
Repeat with the remaining 1/2 heavy cream, using pink food coloring. Refrigerate until ready to use.
Using disposable decorating bags, put each color in a separate bag. Clip a small portion off the end of each bag. Place those two bags into another disposable bag fitted with the Wilton 1M star tip. Making sure you have the ends of all three bags twisted, carefully pipe the whipped cream onto the ice cream cups. You will achieve the swirl easily.
Quickly add a mermaid tail to the whipped cream and decorate with the kits sprinkles. Return ice cream cups to the freezer to set whipped cream (and ice cream if it's begun to melt), at least 1 hour before serving.
Notes
It's good to have extra mermaid tails in the event any break. Store extras in airtight container.