In the second part of this enumeration, the 1841 British edition accidentally dropped the definite article the before sons (giving “the number of sons and daughters of Jared”), perhaps because there was no the before the following daughters. This resulting reading has been retained throughout the LDS textual tradition. The critical text, however, will restore the the before sons in this second part of the passage.
One might wonder if there isn’t some error in this passage, even in its earliest extant form, since in the first part we have “the number of the sons and the daughters” but in the second part “the number of the sons and daughters”. In other words, perhaps the the is missing before the second instance of daughters in this passage. However, when we consider other examples of this conjunctive expression in the earliest text, we find an unexpected systematic relationship: namely, when “sons and daughters” is followed by the actual name of the person, we get “the sons and daughters” (that is, without the repeated the), but when the following specification is a reference to the person but not his name, we get “the sons and the daughters” (that is, with the repeated the):
Although this systematic relationship could be accidental, it makes us pause before emending Ether 6:20 to read “the sons and daughters of the brother of Jared” or to read “the sons and the daughters of Jared”. The critical text will therefore maintain this systematic distinction, based in each case on the reading of the earliest text. (In 2 Nephi 4:3, the 1953 RLDS edition accidentally omitted the repeated the before daughters. For all the other cases, the RLDS text has maintained the earliest reading.)
It should be noted that this restriction on usage is narrowly defined. If, for instance, this expression includes the word fair before son, then the definite article is never repeated before daughter, no matter what kind of postmodification follows; in other words, with the word fair the expression is always the invariant “the fair sons and daughters”:
Summary: Restore in Ether 6:20 the definite article the before sons (“the number of the sons and daughters of Jared”), but no the should be placed before the word daughters (in accord with the reading of the earliest text as well as usage elsewhere in the text).