I think I found a Teretz for my oldest (until now) unanswered Kashya (17 years). Anyone from the Kolel have any other ideas?

(h) Answer (Rav Nachman - Mishnah): A minor can be divorced even from a mid'Oraisa marriage.

1. Question: "Yotzah v'Haysah" equates divorce and Kidushin. A girl who cannot be Mekudeshes (e.g. a minor not in her father's Reshus, e.g. after Nisu'in) cannot be divorced!

2. Answer: A minor is like one who can be Mekudeshes, because she can be Mekudeshes when she matures.

My Kashya - the Gemara (or Rishonim) did not even challenge Rav Nachman from a Mishnah (55a) that says that a Chereshes can be divorced (even if she was married mid'Oraisa through her father), even though she can never be Mekudeshes again! (I later found that one of the not so famous Acharonim asked the question, but I did not see any justification or source for his answer, and I couldn't fathom that the Rishonim considered it obvious and didn't need to mention it.)

My Teretz - perhaps it is understood that any minor can be divorced, even if she is Goses or Tereifah, and barring an unlikely or miraculous Refu'ah, she will never live to adulthood and the possibility of Kidushin. Similarly, a Chereshes can be divorced, even though barring an unexpected Refu'ah, she will never have Da'as and the possibility of Kidushin.

I dont' think that th Sugya or Tosfos address my question at all. They discuss who receives her Get and Kidsuhin, and whose Da'as is needed. They (especially Tosfos 43b DH v'Chol) address the level of Da'as needed for Girushin, but they do nto say that this depends on ability to become Mekudeshes. They do not address Rav Nachman's Drashah, which says that if a girl cannot become Mekudeshes in any way, she cannot be divorced at all, at which my question was directed.