case file № 3 · from The Plunketts

The merge that would have destroyed a generation

Two women who looked exactly like one person duplicated — and the two governments, thirty-four years apart, that proved they were two.

The claim you may have met

That the two Marguerites of the Lefebvre des Hayes family are one woman entered twice, and that the two records should be merged.

Where it comes from: duplicate-detection on the genealogy platforms, which sees two women with overlapping names in the same place and generation and proposes a merge.

What happened

Two women with overlapping names — both Marguerites of the Lefebvre des Hayes family — sat in this tree looking exactly like one person entered twice. The audit had them queued as a top-priority merge. But two lines of this family's descent run through their father, one through each sister: merging them would have collapsed a genuine pedigree collapse into a false one and taken a whole branch of the tree with it.

The first proof they were two people is a single clause inside the 1791 marriage act at Les Cayes: the priest entered a papal vicar's dispensation for consanguinity — the bride and groom were cousins, descended from two different daughters of the old commandant. That is good evidence, but it is exactly the instrument a same-named-sisters error could hide behind.

So it was tested against a completely different bureaucracy. In 1825, France extracted an indemnity from Haiti — payments to the former slaveholders of Saint-Domingue, billed to the people who had freed themselves. The register of that indemnity, compiled thirty-four years after the colony fell and for entirely different purposes, records the two sisters' estates separately, with disjoint lists of heirs: titre 50438 on one side, titres 52685 and 52720 on the other. Two sisters, two estates, two separate lists of heirs.

It has to be said plainly what these documents are. The estates were sugar plantations worked by enslaved people, and the indemnity was compensation paid to the enslavers' heirs. The family's proof of its own structure sits inside the ledger of that injustice — this page cannot be a charming puzzle without saying so.

The records, in order

1 of 3
4 MAY 1791MARRIAGE ACT
A papal vicar's dispensation for consanguinity, entered in the Les Cayes du Fond register.
Bride and groom were cousins through two different Lefebvre sisters — the first proof the sisters were two.
2 of 3
14 AUG 1791REVOLUTION
Bois Caïman: the enslaved people of Saint-Domingue rise.
Fourteen weeks after the wedding. The family runs for the boats.
3 of 3
1825INDEMNITY REGISTER
Disjoint heir sets: titre 50438 against titres 52685 and 52720.
A different government, a different purpose, thirty-four years later — and the same answer: two women.

Two sisters. The merge stays reversed.

The cleanest demonstration in the project of why one source is never enough — the second source was generated by a different bureaucracy, decades later, for reasons that had nothing to do with genealogy.

If your tree carries this line

Keep them as two people. If your tree has merged them, one of the two lines of descent through their father has collapsed into the other and a whole generation has vanished with it. The 1791 dispensation and the 1825 indemnity register, read together, separate them.

What would change it

One loose end would confirm the split from a third direction: identifying which sister was buried at Les Cayes on 14 June 1788 in the original register.

The people in this file

✦ Marguerite Lefebvre des Hayes (c. 1728–1788) · ✦ Marguerite Geneviève Lefebvre des Hayes (c. 1745–c. 1791) · ✦ François Achilles Plunkett (1769–1824) · ✦ Renée Rose Adélaïde Gentillot (1770–c. 1811)