Sounds like parents who want to talk the "I'm-so-involved" talk, but not walk the "I'm-so-involved" walk. I thought you did extremely well with your reply. Explaining the physical limitations of her age was a great idea. I honestly did not get the difference between playing notes and playing music until I was twelve (after five or six years of lessons), and even then it wasn't natural. I had to work at it, which meant the pieces were musical, but I wasn't playing them with feeling. It was forced. Using the dynamics my teacher had written in and adjusting the tempo where she told me to. Thankfully, as you get older and more experienced that all becomes easier. You just get this sense of the phrases and how to express the music. Anyway, I think you did really well. I do think you should mention something about the piano, especially if you think this is restricting her showing any expression in her playing.