Jopie du Plessis — Izelle’s paternal grandfather — carried the full name Josef Johannes Fourie du Plessis. The middle name has two possible readings and it is worth being honest about both.
The first — long assumed — is a maternal-surname carry-forward: a Fourie mother or grandmother somewhere up the du Plessis line, in which case finding her would open a whole new branch. Every Afrikaans naming convention would push you toward this reading.
The second, and now the leading reading, is commemoration naming for Josef Johannes “Jopie” Fourie — the Boer executed by court-martial on 20 December 1914, an instant Afrikaner martyr, “a potent factor in the rise of the National Party”.
The dates fit closer than one might first think. Jopie du Plessis was born on 11 October 1914 — two months before the execution, so the boy was not named at birth for a martyr who had not yet been made one. But DRC baptism on a Free State farm in 1914–15 routinely happened weeks or months after birth. A baptism in January, February or March 1915 — well after the martyr’s death shocked the Afrikaner republican community — is a natural moment for the Fourie middle name to be added or emphasised. Other Afrikaner boys born adjacent to the execution were similarly named: a Jopie Fourie Erasmus surfaces in Gereformeerde Kerk records.
The maternal-surname reading is the one that has weakened. Jopie’s mother is Martha Maria Jansen van Rensburg (1877–1952). Not a Fourie. And of the ten children she and Marthinus Petrus du Plessis raised, only Jopie — the one born in October 1914 — carries the Fourie name. If it were a grandmother’s surname coming down, one would expect it in more than one child.
So the ledger reads: martyr commemoration at baptism explains the timing, the isolation of the name to a single child, and the absence of a Fourie mother. A Fourie grandmother up the line is still possible but there is no positive evidence for one, and the pattern of use is against it. This site follows the commemoration reading.