Basemath

Gen 26:34  And Esau was forty years old when he took to wife Judith the daughter of Beeri the Hittite, and Bashemath the daughter of Elon the Hittite: 

Basemath, Bashemath, or Basmath (Hebrew: בָּשְׂמַת, Modern: Basmat, Tiberian: Bāśəmáṯ, "Sweet-smelling", Arabic: بسمة; "Sweet-smile") is a figure in the Book of Genesis. She was the daughter of Ishmael (or as Genesis 26:34-35 shows, Elon the Hittite), the niece of Isaac, and the third wife of Esau. (Genesis 36:2,3)

Before Esau married his third wife, he had named one of his Canaanite wives after Basemath, probably because he knew of her since they were cousins. The wife whom Esau named as Basemath, was Adah the Hittite, his first wife. So after he married his third wife, Esau changed Basemath the Ishmaelite's name to Mahalath. Esau sought this union with a non Canaanite, in an effort to reconcile his relationship with his parents, namely with his father Isaac whose blessing he sought (Genesis 28:6-9). However, there is no record of his parents' approval for the union of Esau and Basemath (Mahalath). She bore a son, Reuel, to Esau. (Genesis 36:4)

Bashemath bares child

(Gen 36:3)  And Bashemath Ishmael's daughter, sister of Nebajoth.

(Gen 36:4)  And Adah bare to Esau Eliphaz; and Bashemath bare Reuel;

Gen 36:10  These are the names of Esau's sons; Eliphaz the son of Adah the wife of Esau, Reuel the son of Bashemath the wife of Esau.