If it is a favourite, don't tamper with it. I would buy a piece of white fabric and mark on the embroidery pattern of the original. Embroider the same motifs in the same colours and then finish it. Wash the new quilt to make it soft and have it on hand to slowly introduce it to her. That way she can continue to use her old one while getting a new one broken in on a stress-free basis. Depending on her disability, it could be very tramatic to tamper with the original.