Jacob E Schwerin, Who's Your Daddy (and Mommy)?

My sister-in-law's third great grandfather, Jacob Schwerin (b. 1855), seems to have appeared out of thin air.  He and his wife Amelia Kaufman had two children, Nettie (b. 1885) and Monie (b. 1886) in Baltimore.  The 1900 US Census (the last before he died) stated that he and both of his parents were born in South Carolina.  His marriage license (found at the Jewish Museum of Maryland) was more specific:

Marriage License; Jacob E Schwerin & Amelia Kaufman; November 1884

Jacob E. Schwerin, age 29, is said to be from Sumter, South Carolina.  Amelia, age 27, is from Baltimore.  Their marriage was also reported in a local Sumter newspaper, saying that J.E. Schwerin was "formerly of Sumter."

"The Watchman and Southron," December 9, 1884

There was, indeed, one Schwerin family in Sumter during that time, headed by Julius and Caroline (nee Suares) Schwerin.

There are numerous online family trees for Julius and Caroline Schwerin.  While a son named Jacob Henry is mentioned, that Jacob lived only from 1845-1849.  There are no mentions (that I have been able to find) of a son named Jacob born around 1855.

Who were Jacob's parents?  Checking both his grave and his death certificate gave no information.

Jacob Schwerin's Grave--with no parents' names

Jacob Schwerin Death Certificate--with no parents' names

Jacob's death certificate confirms his birth in Sumter, South Carolina, but unfortunately his parents' names are "unknown."  It also says that both of his parents were born in Germany--in direct contradiction to the 1900 census.

Jacob, born in 1855, should appear in the 1860 and 1870 censuses, living with his parents.

1860 United States Census; Sumter, SC; Schwerin Family (lines 29-37)

In 1860, Julius (born in Prussia) and Caroline (born in South Carolina) Schwerin were living in Sumter along with seven children.  Julius was a merchant; the value of his personal estate was $3000 and his wife's was $1500.  There is no mention of Jacob, although there is a child Elia Polak Schwerin who is about the right age.

1870 United States Census; Sumter, SC; Schwerin Family (lines 20-27)

By 1870, some of Julius and Caroline's children (all children and the parents are said to have been born in South Carolina) have moved out of the house, and only 5 remain at home.  Elia Polak Schwerin who had been in the 1860 census has disappeared--replaced by a male about the same age named Keper.  Could Keper be some kind of nickname for Jacob?  Or are these two entirely different people?

Who was Elia Polak Schwerin?

Camden (SC) Journal, October 21, 1851

Elias Polock was in business with J.E. Suares (a brother of Caroline Suares Schwerin), and Elias was also married to Sarah Suares Polock--a sister of Caroline and J.E.  So this is definitely a name in the family, but Elias' young namesake seems to disappear after the 1860 census.  Could the middle initial in "Jacob E Schwerin" be Elias?  Could Elia Polak Schwerin be the same person as Keper Schwerin be the same person as Jacob E Schwerin?  Or are they 2 (or 3) different people?

There are no mentions of any Jacob Schwerins of the right age in South Carolina into the 1870s.  So did Jacob Schwerin apparate fully grown?  Was he a child of Julius and Caroline--or were his parents other people entirely?

Continued here.