[6][7] Her maternal grandfather, Hugh Judson Kilpatrick (1836–1881), was a Union Army general during the American Civil War, who also served as the U.S. minister to Chile.

[4] Her maternal grandmother, Luisa Kilpatrick, née Valdivieso Araoz, was a member of a wealthy Chilean family that had emigrated from Spain in the 17th century.

[12] In October 1921, with their father's permission, Morgan and her sister Thelma, both reportedly 16 years of age, ended their schooling and moved by themselves into an apartment at 40 Fifth Avenue, a private townhouse.

British photographer Cecil Beaton described them as "alike as two magnolias, and with their marble complexions, raven tresses, and flowing dresses, with their slight lisps and foreign accents, they diffuse a Ouida atmosphere of hothouse elegance and lacy femininity.

Reginald Vanderbilt died on 4 September 1925 of what was described in news reports as "a throat infection which had caused internal hemorrhages" [4][15][18] or cirrhosis due to alcoholism.

However, the conditions of Vanderbilt's will and the custody of their child were complicated by the general belief that his widow had not reached the legal age of majority, which meant that she required a guardian.

As a result of a great deal of hearsay evidence admitted at trial, the scandalous allegations of Vanderbilt's lifestyle—including a purported lesbian relationship with Nadezhda de Torby, the Marchioness of Milford Haven,[21][23][24] and a brief engagement to Gottfried, Prince of Hohenlohe-Langenburg[25][21][26]—led to a new standard in tabloid newspaper sensationalism.