Here, as Joseph Smith was editing 𝓟 for the 1837 edition, he initially thought to grammatically emend which to who. He first crossed out the which but then realized that the which refers to the words rather than to the closer nouns Ammon or his brethren. Since the which does not refer to persons, Joseph restored the original which in 𝓟, thus effecting no change at all. The critical text will, of course, maintain the which here—even if it referred to persons. For another example of Joseph’s false starts in editing which’s to who’s, see under Alma 24:13. For a complete discussion of the editing of which to who (or the lack of it), see under which in volume 3.
Summary: Maintain which in Alma 26:1 and elsewhere in the text whenever the earliest textual sources read which.