These statements explain WHY you will not find Sara and her parents together in the census records -
Facts you should know about the early census records - All census records [1790 – 1840] prior to the 1850 census ONLY listed the head of household; whether male or female. NO specific age was stated for any family member NO place of birth was stated – city, state, or country NO city, town, or village is stated – only the county; however some census takers listed the township NO street address was stated NO marital status was stated – single, married, widowed, or divorced NO family relationship was stated – brother, sister, cousin, son, daughter, wife, inlaw, etc… NO occupation was stated NO parental birthplaces are stated NO race was stated [but assume “white”]
1850, 1860 & 1870 census records do not show family relationships, marital status or parental birthplaces.
Step children are not enumerated as “step” children Adopted children are not enumerated as “adopted” Grand children are not enumerated as “grand children” Orphaned children were not enumerated as "orphan"
1850 is the 1st census that shows all family members
1880 is the 1st census that shows parental birthplaces +++
1850 - Name: Dady Bundy Age: 52 Estimated Birth Year: abt 1798 Birth Place: Massachusetts Gender: Male Home in 1850 (City,County,State): Salisbury, Litchfield, Connecticut
Dady Bundy 52, MASS - sailor Sarah A Bundy 47, CT Lucy A Bundy 24, CT Rachel Bundy 13, CT Ezra Allen 22 Louisa Allen 19
1860 - Name: Dady Bundy Age in 1860: 63 Birth Year: abt 1797 Birthplace: Massachusetts Home in 1860: Salisbury, Litchfield, Connecticut Gender: Male Post Office: Salisbury
Dady Bundy 63, MASS - day labor Sarah A Bundy 57, CT  Harvey Bundy 69, MASS - carpenter [could be a brother]
1870 - Neither Dady nor Sarah are listed.
RE:Dady In keeping with naming conventions of the time, Dady may be his mother's maiden name.