Oliver Cowdery initially wrote a complete sentence followed by an unattached predicate. Somewhat later, with somewhat heavier ink flow, he corrected this error by inserting having after the king. This change was probably based on proofing against the original manuscript, especially since the level of ink flow for this supralinear insertion is identical to that of the long supralinear insertion eight lines earlier on the manuscript page (see the discussion above under Mosiah 18:28). It is also possible, of course, that the insertion was simply Oliver’s attempt to correct a defective sentence. An alternative solution, if he had simply been correcting the text on his own initiative, would have been to insert an and before the verb form sent, which would have given two coordinated predicates: “the king discovered a movement among the people and sent his servants to watch them”.
There is one clear example where Oliver Cowdery accidentally omitted the present participle having while copying from 𝓞 into 𝓟 but then almost immediately supralinearly inserted having (there is no change in the level of ink flow):
In this particular instance, 𝓞 is extant and reads having, so we know that Oliver’s correction is not his own emendation to the text. The most reasonable assumption in Mosiah 18:32 is to assume that Oliver corrected 𝓟 according to the reading in 𝓞 (as in Alma 58:23).
Summary: Accept in Mosiah 18:32 Oliver Cowdery’s insertion in 𝓟 of having; this correction probably represents Oliver’s proofing against the original manuscript rather than his own editing.