Who was Duncan Grant (b:1816) 1st wife????

According to a book called. Descendants of Duncan Grant, Marlboro County, South Carolina written by Jerry T. Kendall. Showing Duncan/Sarah having 9 children. But according to the 1850 Census. Listed below Duncan/Sarah have a son named Henry P. Grant.born in 1839. Which would make Sarah 14 years old when she had him. My Aunt told me about her Great-Grandfather and my Great-Great Grandfather Henry Grant . Mother dieing after giving birth to him. That she was an daughter of Indian Chief (Elder). The family disapproved of her. Making Henry the black sheep of the Family. Show if you add Henry to the list of children you now have 10 children for Duncan, And 9 children for Sarah. Does anyone have any information about Duncan 1st wife?

Duncan D Grant, b: 1816 married Sarah Smith B: 1825
Children: 10
Grant, Henry P. b: 1839 ( Unknown mother) (Father: Duncan Grant)
Grant, Alex b: 1844
Grant, Amanda b: 1846
Grant, John P b: 1848
Grant, Charles Wesley b: 1849
Grant, William b: 1851
Grant, James Oliver b: 1861
Grant, Malachi b: 1860
Grant, Henry T b: 1864
Grant, Dicy b: 1866

1850 United States Federal Census
about Duncan Grant
Name: Duncan Grant
Age: 34
Estimated Birth Year: abt 1816
Birth Place: South Carolina
Gender: Male
Home in 1850(City,County,State): Marlboro, South Carolina
Household Members: Name Age

Duncan Grant 34 Farmer
Sara Grant 25
Henry Grant 11
Alex Grant 6
Amanda Grant 4
John Grant 1
>>>>Aggy Grant 79