Complex sentence: His pupils, who aided him much in his work, were his wife's brother, Theodore Goussé, and three brothers of his own, as well as Claude Lefèbvre and Pierre Patel the landscape painter.
Split into simpler sentences: His pupils, who aided him much in his work, were his wife's brother, Tb. Gouss, and three brothers of his own, as well as Claude Lefèbvre and Pierre Patel the landscape painter.