DNA Connections
It may be possible to confirm family relationships with Gerrit by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share some percentage of DNA with Gerrit:
The baptismal record should be used to validate the spelling of the LNAB (Last Name At Baptism) or surname.
The LNAB in this instance is Van Nieuwkerke.
Van Niekerk could be added to the Current Last Name if a subsequent record indicates this other last name.
Van Niekerk-1676 and Van Niekerk-977 appear to represent the same person because: Gerrit is the great-great-great-grandfather of Maria Adriana (Dia) Labuschagne [Kruger]; wikitree profile: https://www.wikitree.com/wiki/Kruger-4160
The LNAB in this instance is Van Nieuwkerke. Van Niekerk could be added to the Current Last Name if a subsequent record indicates this other last name.