Complex sentence: On 22 March 1770, Frederick married Margaret Caroline (died 27 Jan 1824), daughter of Granville Leveson-Gower, 1st Marquess of Stafford and his wife Louisa, who was in turn daughter of Scroop Egerton, 1st Duke of Bridgewater.
Split into simpler sentences: On 22 March 1770, Frederick married Margaret Caroline Leveson-Gower (died 27 Jan 1824). Margaret was a daughter of Granville Leveson-Gower, 1st Marquess of Stafford and his wife Louisa, who was in turn daughter of Scroop Egerton, 1st Duke of Bridgewater.