Here in the original manuscript, Oliver Cowdery initially wrote “and the dissenters of the Nephites”; somewhat later, probably when he read back the text to Joseph Smith, he supralinearly inserted all before the dissenters (his correction is written with somewhat heavier ink flow). Since the all is not necessary, it probably represents the reading of the original text.
A similar supralinear correction with somewhat heavier ink flow was also made in this passage. Oliver Cowdery initially wrote “which was composed of the Lemuelites and the Ishmaelites”, thus omitting any reference to the Lamanites proper. His omission was probably the result of him just having written “among all the people of the Lamanites”. Later Oliver surpralinearly inserted “Lamanites & the” in 𝓞. This correction seems to have been done at the same time the all was inserted (namely, when Oliver read back the text to Joseph Smith). Elsewhere, when the text refers to the tribes that belonged to the Lamanites, the reference is always to Lamanites, Lemuelites, and Ishmaelites:
Summary: Maintain in Alma 47:35 the two corrected readings in 𝓞, namely, the addition of “the Lamanites and” (before “the Lemuelites and the Ishmaelites”) and the all (before “the dissenters of the Nephites”).