To be clear, when talking about the sister of St-Clair's kid, we are talking about Vivian, Elon, and Justine's kid, who is technically the half-sister of Elon and Ashley St-Clair's kid.
— Fred Lambert (@FredLambert) January 12, 2026
"half-sibbling" is a term that I dislike, but it is helpful for clarity in this case.