Complex sentence: Her eldest brother Henri Bergson joined the faculty of the College of France, is best known for authoring the philosophical work "Creative Evolution", and was also the president of the British Society for Psychical Research.
Split into simpler sentences: Her eldest brother, Henri Bergson, joined the faculty of the College of France and is best known for authoring the philosophical work "Creative Evolution". He was also the president of the British Society for Psychical Research.