What about an embryo created through IVF and kept frozen, whose father died during the time it was frozen? On the one hand, this is an embryo that already existed during the father’s lifetime (unlike sperm that was retrieved after death), but on the other hand the embryo has not yet been returned to the mother’s womb, and there are halakhic decisors who even permit killing it in such a state. And if it has no right to life, then all the more so it would have no right to inherit.

Did you see the article I linked to? It says there that according to all opinions, a fetus inherits once it is born (there is a dispute about what happens in the meantime). I don’t see why there should be any difference here. Even for a fetus there is no prohibition of murder “You shall not murder” (except according to the view of Igrot Moshe), and still it inherits. Especially if this works retroactively, then it does not need to be a person at the moment of inheritance; rather, once it is born it inherits retroactively.