When copying from 𝓞 into 𝓟, Oliver Cowdery initially wrote “the branches of the wild tree have taken hold”, which is correct according to standard English grammar, but then almost immediately Oliver corrected the have to hath (there is no change in the level of ink flow for the supralinear hath). Undoubtedly, the original manuscript (not extant here) read hath. Present-tense verbs with plural subjects frequently took the biblical third person singular ending -(e)th in the original Book of Mormon text. In accord with standard English, the 1920 LDS edition replaced this hath in Jacob 5:18 with the plural have.
Similarly, in his editing for the 1837 edition, Joseph Smith replaced the instance of hath in “the wild branches hath brought forth wild fruit” with have. In this second case, the 1905 LDS edition unintentionally restored the hath; the typesetter was probably influenced by the similar phraseology of the preceding “the root thereof hath brought forth much strength” (where the subject noun root is in the singular and therefore hath has never been edited to have). The 1911 LDS edition followed the 1905 hath, but the 1920 LDS edition restored the grammatically emended have that had been earlier introduced into the 1837 edition. For a complete discussion of this variation in the text, see infl al endings in volume 3.
Jacob 5 has many similar examples of the editing of hath to have, providing the subject is plural:
The last example is somewhat different in that the original form hath takes the second person plural pronoun ye as its subject (“ye have … and have … and hath”). In fact, this last passage may have read “ye have … and have … and it hath” in the original text. For discussion, see under Jacob 5:75.
Summary: Maintain the original use of hath with plural subjects whenever it is supported by the earliest textual sources (twice here in Jacob 5:18 and elsewhere in Jacob 5).