Family Search (which I don't always credit for anything but sources) has listed Samuel Sarvis as the son of Samuel Sarvis and "unknown."
It gives a birthdate of 1770 and a death date of 1859, but no source for death date and no census.
From Ancestry, an older Samuel "Service"
Source Citation
The National Archives in Washington, DC; Washington, DC; First Census of the United States, 1790.; Year: 1790; Census Place: Prince Georges, Georgetown, South Carolina; Series: M637; Roll: 11; Page: 507; Family History Library Film: 0568151
Description
Township: Prince Georges
Source Information
Ancestry.com. 1790 United States Federal Census [database on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2010. Images reproduced by FamilySearch.
Original data:First Census of the United States, 1790 (NARA microfilm publication M637, 12 rolls). Records of the Bureau of the Census, Record Group 29. National Archives, Washington, D.C.
Samuel was not born until after the 1790 census it appears so will need to find an 1800. I think I have a hard copy in my files somewhere.
Samuel is not named in the detailed will of John Sarvis, II The different parent would explain the situation.
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1810 census for Samuel Sr.
Name:
Saml
Name Variation
Service
User corrections:
[Saml]
Name Variation
[Sarvice]
Name Variation
[Saml]
Name Variation
[Sarvice]
Name Variation
Residence Date:
6 Aug 1810
Residence Place:
Horry, South Carolina, USA
Free White Persons - Males - 45 and over:
1
Free White Persons - Females - 16 thru 25:
1
Free White Persons - Females - 45 and over:
1
Number of Household Members Over 25:
2
Number of Household Members:
3
--------------------------------
1810 for Samuel Jr.
Name:
Saml
Name Variation
Service
User corrections:
[Saml]
Name Variation
[Sarvice]
Name Variation
[Saml]
Name Variation
[Sarvice]
Name Variation
Residence Date:
6 Aug 1810
Residence Place:
Horry, South Carolina, USA
Free White Persons - Males - Under 10:
1
Free White Persons - Males - 26 thru 44:
2
Free White Persons - Females - 10 thru 15:
1
Free White Persons - Females - 26 thru 44:
1
Number of Household Members Under 16:
2
Number of Household Members Over 25:
3
Number of Household Members:
5
Samuel Sr. and Jr. lived next door to each other according to the census. Then the house of William Suggs? and then John.
The Samuels are noted as Jr. and Sr.