He was a widower with ten children aged between two and nineteen; she had a 13 year old daughter Louisa and an adopted daughter aged about 17, Elencho Marie (later known as Ellen Mary).
In 1851, Marian and her new husband took ship to America with eleven of their children, a lapdog, six canaries and a parrot [cf Remarkable, but still True, chapter 18].
Digby Beste's lively account of the family's travels can now be read online: The Wabash: or Adventures of an English Gentleman's Family in the Interior of America, Volumes one and two.
He includes many lively and fluent contributions written by his children. He had set them the task of writing something each day as an exercise in composition and handwriting. When, as he explained in his Preface to volume one,
these descriptions appeared to me graphic or entertaining; when they told the sad scenes which I myself was incapacitated from witnessing; when, even, they only showed the impressions which a new country and new scenes produced upon new mindshe incorporated them in his text. Those of his stepdaughter Louisa Barlow Hoy can be found by searching for "Louie".
Several of the party fell seriously ill with dysentery while they were staying in a hotel in Terre Haute, Indiana, and 9 year old Isabel died there on 10 July 1851.
Her sister gives a touching account (pages 38 & 39) of the poor child's death and funeral, with grateful notice of the number of strangers who attended the funeral of "the little stranger of whom they knew nothing, and to show their sympathy for the family".
Details of her grave can be found here, at Find A Grave.