The original manuscript is not extant for the word unto, although spacing between surviving fragments has room for the entire unto rather than the shorter to that scribe 2 of 𝓟 originally wrote when he copied the text from 𝓞 into 𝓟. In correcting 𝓟, scribe 2 supralinearly inserted the correct unto but neglected to cross out the to. Since either unto or to will work here, scribe 2’s unto undoubtedly reflects the reading in 𝓞. The critical text will maintain the preposition unto.
Summary: Accept in Alma 11:45 the correcting unto in 𝓟 as the reading of 𝓞; there would have been no motivation for scribe 2 to have corrected to to unto except that 𝓞 read that way.