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Q. In the following sentence, is a comma required (or even recommended) before “and her ten-year-old son”? “She is especially distraught when her preteen daughter, Pam, rebels by befriending a navel-pierced neighbor and her ten-year-old son, Joe, betrays her by making contact with the father.” I see this clause as being introduced by the same when that introduced the clause before it, and I would opt for no comma. Since the sentence is long, would it be acceptable to repeat the word when before the other clause? (“She is especially distraught when her preteen daughter, Pam, rebels by befriending a navel-pierced neighbor and when her ten-year-old son, Joe, betrays her by making contact with the father.”)
A. Adding when is a fine strategy, but there’s nothing wrong with using a comma. Something must be done: otherwise, readers may assume that Pam befriends the neighbor and the neighbor’s son, and we stumble when the son turns out to have a different verb (and a different mom). While it might be technically correct to omit a comma between compound objects, it’s usually not correct to ambush the reader, and it’s always correct to use a comma to untangle a long and misleading sentence.