The question here is whether the relative clauses are restrictive or nonrestrictive; that is, should there be commas separating these relative clauses? In the current text, the last two relative clauses (which have the form “whose name was X”) are separated from their antecedents by commas. But the first relative clause is not (“and his brother whom he had raised from the dead”). The 1830 edition had a comma, but the 1837 edition dropped it (perhaps accidentally). The question is: Is the relative clause “whom he had raised from the dead” telling us which brother of Nephi’s was one of the twelve? In fact, one could ask if the use of “whose name was Jonas” was to tell us which son was chosen. My own inclination is to give a nonrestrictive interpretation to all three of these relative clauses. Nephi has one brother and one son (or only one of each with respect to membership in the twelve). Presumably, “his son” refers to the son of Nephi, not the son of Timothy, but one cannot be sure. The use of the also supports that reading.
Overall, this interpretation suggests that a comma should be placed in front of the first relative clause, so that all three relative clauses are nonrestrictive. One might also use dashes to indicate that “also his son” refers to Nephi’s son:
Summary: The punctuation in 3 Nephi 19:4 should be revised to show nonrestrictively that Nephi had raised his brother, one of the twelve, from the dead and that the name of this brother was Timothy; dashes could be placed around these two nonrestrictive relative clauses in order to show that the later reference to “his son” is a reference to Nephi’s son rather than Timothy’s; and finally, a comma after “his son” would show nonrestrictively that the name of this son was Jonas.