Ambrose Madison married Frances Taylor, daughter of Col. James Taylor Jr. and Martha Thompson Taylor on 24 Aug 1721 in King and Queen County, Virginia. The Madison family moved to the plantation in 1732 after a house had been built and tobacco cultivation had started. They had several children, and their oldest son was James Madison, Sr., the future father of U.S. President James Madison.
James Sr’s two younger sisters, Frances and Elizabeth married into substantial families. Frances Madison wed first Taverner Beale and second Jacob Hite. Elizabeth Madison wed first john Willis and second Richard Beale. 
Frances' husband died at age 36 after a short illness, on August 27, 1732. She was left with a large plantation and 29 slaves. She never remarried.
Frances was born 30 Aug 1700. She died Nov 1761 in Mount Pleasant, Orange County, Virginia from smallpox and was buried Nov 1761 in Madison Family Cemetery.
Plot: National Park Service map indicates she & her husband are possibly buried in front of Pres. Madison's monument.
"Frances, wife of Ambrose Madison, departed this life October 25, 1761 and was interred the Sunday following at Montpelier, in Orange. Her funeral sermon was preached on Wednesday, the 30th of December..”
↑ Ireland, John Robert. History of the life, administration and times of James Madison, Fourth President of the United States: Struggle for Constitutional Government and second War with England.
Fairbanks & Palmer, 1886 - 564 pages
It may be possible to confirm family relationships with Frances by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Frances: