Markus Foster married Peggy Roberts 23 February 1836 in Wayne Co. KY. Surety, Wesley Branscom. This is the same Markus Foster who married Betsy Owens 22 August 1821 in Wayne Co. KY. Surety, Jacob Steel. (Wayne Co. VR - Died, Mark Foster, October 1854 on "R" Creek of consumption age 59 years, married, born in Wayne, son of Charles and S. Foster.)
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Kentucky, Death Records, 1852-1965
Name: Mark Foster, Gender: Male, Death Age: 59
Birth Date: abt 1795, Birth Place: Wayne, Residence Place: Wayne, Kentucky, USA
Death Date: Oct 1854, Death Place: Wayne, Kentucky, USA
Father: Charles Foster, Mother: S Foster
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Name:Mark Foster
Home in 1840 (City, County, State):Wayne, Kentucky
Free White Persons - Males - 5 thru 9:5
Free White Persons - Males - 10 thru 14: 3
Free White Persons - Males - 15 thru 19: 1
Free White Persons - Males - 40 thru 49: 1

Free White Persons - Females - Under 5: 2
Free White Persons - Females - 5 thru 9: 1
Free White Persons - Females - 10 thru 14: 2
Free White Persons - Females - 20 thru 29: 1

The L.D.S Ancestral File lists a 2nd husband, William Slavey, b. abt 1845, for Margaret. Margaret was born about 1810 - 1812 which seems highly unlikely for a marriage to someone about 33 years her junior. However, the following was found in the census records of Wayne Co., Kentucky and Collin Co., Texas.
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1870 Wayne Co., KY - US Fed. Census
Roll M593_503, page 15, Monticello, 27 July
202, 202
Slavey, William, age 25, M/W, Farmer, b. KY
" Margaret, age 60, F/W, Keeping House, b. KY
Foster, Telitha, age 25, F/W, At Home, b. KY
" Octavia, age 5, F/W, b. KY
" John, age 4, M/W, b. KY
" Susan, age 2, F/W, b. KY

(William Slavey married Rebecca E. Foster in 1868. Rebecca has to be the Elizabeth Foster listed in the household of Marcus Foster in 1850. In 1860 she was listed in another household as a domester servant. Rebecca Elizabeth must have died before 1870. Although, Telitha was married at this time to Jeremiah Heath, he is not listed. The above children; Octavia, John and Susan are the children of Telitha and Jeremiah)
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1880 Collin Co., TX - US Fed. Census
Roll 79_1296, Page 239.3, 5 June
84, 86
Slavy, William, age 35, Farmer, b. KY, KY, KY
" Margaret, age 69, Wife, Keeping House, b. KY, KY, KY
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Bethel Cemetery, Frisco, Collin Co., Texas
Margaret shares a headstone with her daughter Telitha:
Margaret Slavey: 1800 - 1894
Telitha Jamison: 1839 - 1925
(Findagrave.com)