Take a deep breath Grandma. Just make some dishes. It isn't a big deal unless she makes it a big deal. I assume she wants to make things that her granddaughter enjoys. Soooo, go learn about quinoa and other grains and whatever and make her some tasty dishes like a loving grandma. Doesn't mean that she has to sink the traditional Thanksgiving and not make her usuals. Do that but have some other side offerings and bread. Done deal.