A genealogy in the Hebrew Bible almost always repays slow reading. The Targumist on (Genesis 11:29) drops a single clause into the list of wives and changes the whole family tree: Iska, who is Sara.
In the plain verse Nahor marries Milcah, and a sister named Iska is mentioned and then never appears again. Targum Pseudo-Jonathan — following a tradition also preserved in the Babylonian Talmud (Megillah 14a) — tells you the missing name belongs to a woman you already know. Iska is Sarah. The matriarch whose laughter will one day shake the tent of Mamre has been standing in the genealogy all along, hidden under an earlier name.
Why two names? The Targumist and the Sages play with the Hebrew. Iska is related to the verb to gaze, and Sarah, they say, was a woman into whom all eyes gazed — for her beauty and for her prophetic sight. She saw by the Holy Spirit. She was also seen, constantly, as a presence no room could ignore.
This is a small sentence with a large theology. The matriarchs are not introduced in the Hebrew Bible the way the patriarchs are — there is no named call, no covenantal monologue. So the rabbis and the Targumist smuggle Sarah into the record earlier, sliding her name under a second name, so that by the time Abram leaves Haran she is already established as a seer and a beauty, a daughter of the same grandfather as Milcah, knit into the lineage before the covenant begins.
The lesson is quiet. Sometimes the people most essential to a story enter it under a name the reader does not yet recognize.