Link is able to fuse Green Kinstones with Dottie at various points in the game. As it is a Green Kinstone fusion, it is not set to a specific treasure chest, but instead, one of the many possible treasure chests. There is also one random Red Kinstone fusion in the game and Dottie is one of the characters that Link can fuse that one with.
She is a very observant women, looking out for the surroundings in town. Early in the game she notices that one of the vendor stalls is dirty, so one of the guys won't be setting up shop. This is a clue for Link to cleanup the dust using the Gust Jar. After Link clears the dust, Dottie will make another observation that it is nothing but fruits and veggies, referencing Pina and Brocco the fruit and vegetable vendors.