Ociee Nash was an actual person, the grandmother of author Milam McGraw Propst, who penned the novel "A Flower Blooms on Charlotte Street" from which the screenplay was drawn. The real Ociee Nash was born in 1889 and was 9 years old in 1898 - the year in which the film is set, and the age of the on-screen title character.
The character of Harry Vanderbilt was based generally on the Vanderbilt family, of which, George Washington Vanderbilt II (the youngest son of the third generation of the family founded by Commodore Cornelius Vanderbilt) purchased a large tract of land in Asheville, North Carolina (where the story in this film is largely set) in 1889 to build the largest mansion in the United States, Biltmore, which had it's grand opening celebration on Christmas Eve, 1895. GW Vanderbilt did not have any sons or younger brothers. His only daughter, Cornelia, was not born until 1900.