I don't think Elwing could have known her grandmother, according to Tolkien's chronologies Beren and Luthien die before Elwing is born.
However Elwing grows up surrounded by Elves of Doriath who undoubtedly told her a great deal about her grandmother, how much they loved her and missed her and how like her Elwing was. Add in all the Elven kin she meets in Aman, including possibly her great grandmother Melian still grieving for the daughter she's lost. And one can see how Elwing might have felt she just couldn't put them all through that kind of loss all over again.
Besides she may have simply identified more with her Elven side, and maybe she liked what she'd seen of Aman and her kin there.
|