Complex sentence: She is the older sister of the 8th Marquess of Bristol and of Lady Isabella Hervey, and her older half-brothers were the 7th Marquess of Bristol and Lord Nicholas Hervey, both deceased.
Split into simpler sentences: She is the older sister of the 8th Marquess of Bristol and of Lady Isabella Hervey. Her older half-brothers were the 7th Marquess of Bristol and Lord Nicholas Hervey, both deceased.