Is it possible to add light-colored food coloring to dark chocolate fudge and have the color turn out right?

I want to make this watermelon fudge recipe but want to use the box of fudge mix I bought from the store instead of making it from scratch like the recipe says. To get the watermelon colors I was going to use the pink and green food coloring of course and also buy some watermelon extract to get the watermelon taste as the recipe states. Would my way work or would the pink food coloring dye mixed with the brown fudge make a tan color and green food coloring dye mixed into the dark brown fudge make like a diarrhea greenish brown color?

bon appetit