Complex sentence: The Geste brothers are orphans and have been brought up by their aunt, the rest of Beau's band are his cousins Isobel and Claudia and Lady Patricia's relative Augustus.
Split into simpler sentences: The Geste brothers are orphans and have been brought up by their aunt. The rest of Beau's band are his cousins Isobel and Claudia, and Lady Patricia's relative Augustus.