Ok, I’ve made an error, and I’m not going away without correcting it.
In
Unfinished Tales, in the Appendix to “Númenórean Linear Measures”, Christopher Tolkien quotes his father’s notes,
She was known as Morwen of Lossarnach, for she dwelt there; but she did not belong to the people of that land. Her father had removed thither, for love of its flowering vales, from Belfalas; he was a descendant of a former prince of that fief, and thus a kinsman of Prince Imrahil. His kinship with Éomer of Rohan, though distant, was recognized by Imrahil, and great friendship grew between them. Éomer wedded Imrahil’s daughter [Loth*riel], and their son, Elfwine the Fair, had a striking likeness to his mother’s father.
I found this perusing
Reader’s Companion after reading
LotR for about the one hundredth time. My apologies for the confusion.