Lady Diana has a very important point. Peroxide breaks down organic molecules. It's great for removing organic stains, such as pet mess, from non-organic fibers such as nylon carpet. The organic dyes that might be in the old quilts could easily be harmed by it. I think because of the significance of these quilts in your family it would be best to get professional advice from a museum. I'm so sorry for the trauma of having a fire in your home.