Complex sentence: Guillaume de Rougemont (1945) Arthur (1947) and Moya (1950) Hayden and in 1955 she married amateur rider John Ciechanowski and had a son (Alexander 1956) with him.
Split into simpler sentences: Guillaume de Rougemont (1945) Arthur Hayden (1947) and Moya Hayden (1950). In 1955 she married amateur rider John Ciechanowski and had a son (Alexander Ciechanowski 1956) with him.