WHEN RAFFAELE FABRIZIO was growing up, he lived in a small village close to Lake Como called Fino Mornasco that was near the headquarters of Dedar, the Italian fabric house that his parents, Nicola and Elda, founded in 1976. Fabrizio, 55, and his sister, Caterina, 56, have spent their careers at Dedar, bringing the firm into a new era by introducing novel combinations of color, pattern and texture, attracting clients like Hermès and the movie director Luca Guadagnino.