John Tyler was married when he unexpectedly became president, but his wife, Letitia Tyler, was ill. She died in 1842 while Tyler was still President. While Tyler remarried while in office, his daughter (Letitia Tyler Semple) and his daughter-in-law (Priscilla Cooper Tyler…coming later this week) filled in after his first wife’s death as well as helped out Letitia Tyler while she was alive.
The National First Ladies Library biography of Letitia Tyler provides a nice synopsis of Letitia Tyler Semple as well:
The spring 1844 social season at the White House was presided over by President Tyler's daughter Letitia "Letty" Semple, born on 11 May, 1821. Although Letty Semple and her sister Lizzie Tyler (previous to her February 1842 wedding), and on at least once occasion their eldest sister Mary Tyler Jones were on hand at White House social events to welcome guests, the President had specifically designated his daughter-in-law Priscilla Tyler as his official hostess. When she moved to Philadelphia, the social responsibilities briefly fell to Letty Semple.
In February of 1839, eighteen year old Letty Tyler had married Captain James Semple, U.S.N. of Virginia. From the start their marriage was stormy and the President sent Semple on a three year assignment at sea as a means of postponing any potential divorce between Semple and his daughter. Tyler implored Letty and her sister Elizabeth and Alice to "Show no favoritism, accept no gifts, and receive no seekers after office.” Dolley Madison advised the Tyler women to return all social calls in person - as she had done, thus temporarily restoring her own custom which had been done away with by her immediate successor Elizabeth Monroe; accordingly three afternoons a week. Letty Semple, Lizzie Tyler and their sister-in-law Priscilla Cooper Tyler devoted themselves to this duty. Despite the financial straits of the Tylers, the President insisted on entertaining lavishly, and so they held two dinners each week in the social season for about forty Congressional guests, and one public reception.
The three months that Letty Semple presided as the sole hostess of the White House (March to June 1844) for her widowed father was unremarkable. She was shocked and hurt when, in June 1844, her father remarried and she was no longer the hostess of the White House, replaced by a woman her own age. While the other Tyler children soon took to their new stepmother, Julia Gardiner Tyler, Letty Semple never did. Refusing to show her the most basic civility, Letty Semple forever resented her stepmother and there would be no reconciliation. Later, when the widowed Julia Tyler helped James Semple during a difficult financial period in his life, Letty Semple wrote her estranged husband that while they would not divorce, she no longer considered him her spouse. It is not clear at what point following her father's remarriage Letty Semple moved out of the White House; since the new president's wife was in Virginia and then New York with Tyler in the summer months following their elopement, and did not take up full residence in the mansion until the fall of 1844, it is likely that Letty Semple returned to her father's home in Williamsburg during that period. John Tyler managed never to alienate his daughter permanently but after his death, Letty Semple struggled on her own.
During the Civil War, Letty Semple lived in the town of Chatham, Virginia in the log kitchen dependency of the Col. Coleman D. Bennett property, located behind the Bennett home on North Main Street. Entrusted with the care of three nephews and nieces after the war, and destitute financially, she moved to Baltimore and managed to find enough financing to open a school, the Eclectic Institute for young women. Two of her students were from Canton, Ohio, the hometown of the future president and his wife, William and Ida McKinley. In the 1870's Letty Semple was given free room and board for the rest of her life by her friend, Washington entrepreneur W. W. Corcoran, at the Louise Home, which he created for elderly women of distinguished background who found themselves in genteel poverty. He was her escort to the numerous White House events she was invited to by Lucy Hayes, and the First Lady befriended and often visited Letty Semple at the Louise Home. She was a frequent White House guest of the President and Mrs. McKinley, and Ida McKinley often put her horse and carriage at Letty Semple's disposal. Mrs. Semple denounced what she called “the atrocious butchery” of the 1902 White House renovation and would not enter the mansion during the Theodore Roosevelt Administration. Letty Semple prominently hung the only life oil portrait of her mother over the mantle in her bedroom at the Louise Home, always considering Letitia Tyler to have somehow been the only legitimate wife of her father, the tenth President. She died on 28 December, 1907, during a trip to Baltimore, Maryland.
There was a nice article about Letty Semple from The Ladies’ Home Journal in 1897:
In the luxurious retirement of the Louise Home at Washington, D. C., the eldest living daughter of a President of the United States, Mrs. Letitia Tyler Semple, daughter of John Tyler, who succeeded to the Presidency upon the sudden death of President William Henry Harrison, is now passing her days. Her mother, who was in delicate health when Mr. Tyler became President, died shortly afterward. During the period of Mrs. Tyler's invalidism her daughter-in-law, Mrs. Robert Tyler, presided at the White House. After the death of Mrs. Tyler, which occurred in September, 1842, President Tyler invited Mrs. Semple, who was residing at her home in Virginia, to take up her residence at the White House. She was able to do this without difficulty, as her husband had been appointed a Purser in the Navy, and was then at sea. Thus, until her father's second marriage, Mrs. Semple occupied the high position of mistress of the Executive Mansion.
When the Civil War began Mrs. Semple hastened from Brooklyn, where she was living, to Williamsburg, Virginia, where she aided in the establishment of hospitals, and in the arrangements made for the care of the sick and wounded. At the close of the war she established a school for young ladies in Baltimore, and later accepted the munificent provision made by the late W. W. Corcoran for just such ases as hers, when he founded and perpetually endowed the Louise Home at Washington as a luxurious and congenial home for gentlewomen of fallen fortunes.For more information on Letty Semple as well as other presidential families you can read Gilson Willets’ Inside History of the White House (1908) online through Google Books.