Have you tried just saying it to her? If I were in your shoes, I would leave little gifts like chocolate at her school desk or at her front porch. I would just leave a little note about me and see if they would catch on to who I am. You can also start to get closer to them like asking to sit by them during lunch or hang out at a park. After a while I recommend telling them. You can also show them your special talent and see if they are impressed