Complex sentence: William Charles Kingsbury Wilde (1852--1899) who became a journalist and poet, Oscar Fingal O'Flahertie Wills Wilde (1854--1900) who became a prolific and famous writer, and Isola Francesca Emily Wilde (1857--1867) who died in childhood.
Split into simpler sentences: William Charles Kingsbury Wilde (1852--1899), Oscar Fingal O'Flahertie Wills Wilde (1854--1900), and Isola Francesca Emily Wilde (1857--1867). Her eldest son William became a journalist and poet, her younger son Oscar Wilde became a prolific and famous writer, and her daughter did in childhood.