According to some accounts, Indis may have been among the first Elves to awaken at Cuiviénen, and taken part in the Great Journey. It's unclear whether Tolkien intended that conception to stand, but at the very least we can be sure that she was present in Aman during the Years of the Trees.
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The nature of Indis' relationship with Ingwë is open to question. In some texts, she is described as his sister, but in others she is his sister's daughter (and therefore his niece).