Mixed Blood

[Aiwendil]

Thus it was only to one mixed line that the Choice was granted, not to all half-elves by blood. Mithrellas was not of the right line.

This was, however, written in the late 1930s, before the characters Elladan, Elrohir, and Arwen existed - so I wouldn't say it's entirely conclusive. Personally, I had always interpreted the "choice" as being inclusive of Elrond's children (though not of Elros's) since the Valar did not have the authority to revoke the Gift of Iluvatar from anyone. However, I have no evidence for this and I'm not sure whether it has some textual basis or not.

I do think, though, that the depiction of the sorrowful parting of Elrond and Arwen in LotR makes more sense if Arwen's choice is understood as a choice for mortality. It always seemed to me that Elrond expected never to see his daughter again.

[Gordis]

Originally Posted by Aiwendil

I do think, though, that the depiction of the sorrowful parting of Elrond and Arwen in LotR makes more sense if Arwen's choice is understood as a choice for mortality. It always seemed to me that Elrond expected never to see his daughter again.

I never doubted it. As a matter of fact it is stated rather plainly in LOTR:

Arwen Evenstar remained also, and she said farewell to her brethren. None saw her last meeting with Elrond her father, for they went up into the hills and there spoke long together, and bitter was their parting that should endure beyond the ends of the world.

I think" to Earendil and Elwing and their sons" includes all their possible offsprings in the following generations. Elros had the choice and Elrond and Elrond's children. Elros had chosen mortality and became a Man - thus his children were not half-Elven anymore.
In the case of Elrond's children it is only strange why the Choice was made so late: when they had already lived for almost 3000 years. Why wasn't it offered much earlier, around the time when they lived for one human life-span?

[Findegil]

It is stated some were, I think in Appendix A, that a special choice was granted Arwen, that she could remain in Middelearth in the youth of the Eldar, as long as Elrond remained, but he left for Valinor she had to make her choice either to leave with him and life on as one of the Eldar or to remain in Middleearth and become a mortal.
In of the Letters Tolkien said that her brethern would natrualy have the same choice but that they could in what ever way delay it. That means that we can not be sure that both of them choose to be mortal also we here that they stayed behind when Erond left.

Respectfully
Findegil