How do I get this girl to stop copying my drawings?

Well last year (in school) I had this drawing style and it wasn't good at all but i drew them often, and well this girl lets call her , Birdie, started drawing them too. Well now its next year And i actually draw better i mean way better and now shes trying to draw like me again in the new better style that i have. Shes in a different class this year and one of her friends drew in my style and i didn't want to be like 'YOU COPIED ME!!COPIER!!' Because well she could of thought of it too. I asked her if she made it up herself and she said she got it from Birdie. I always used to show birdie my drawings and new techniques but...now i realized that she could just be copying me in every drawing and technique i show her. And i would never know because shes in a different class. Well and how i know she copys is because one of her friend lets call him John Doe said 'Birdie drew one of these Cupcakes and a baby one too! They were so cool.' And earlier that day i had been doodling and drew a big cupcake and a baby while watching a movie in Gym. And when i draw infront of her and she trys to draw like me (i can tell) she gets sad like..she'll get all quiet and start to just stare at me drawing studying my every move. Then she trys and shes all like i can't draw at all and i try to encourage her to make up a style that shes good at and try something new. But she still seems to copy me in every drawing she shows me. Sometime when i show her one of my new styles she calls it ugly and i need to 'work' on it (which kinda makes me sad) then later that day or week i see her drawing the same thing. Well how can i tell Birdie to stop in a nice way but not like ' Stop copying me i know you want to be like me' way like....i need a style that she can actually do without it being similar to mine. It really bothers me that the people in her class think that shes so original and creative when i come up with all the stuff she draws. Please its really annoying.