Q. You advocate using the serial (Oxford) comma in all applications, correct? If so, I disagree. For your consideration: when omitting the comma does not alter the meaning and, more important, the flow of the sentence, it should be omitted (e.g., I became friends with Jim, Barbara and their aunt).
A. Although Chicago favors the use of the serial comma as a default style and would therefore put a comma after Barbara in your sentence, our guidelines are not meant to be applied “in all applications” without thought to meaning or usefulness. They are meant to be applied with judgment and flexibility. We have stated this in every edition since the first one in 1906, and we hammer on it constantly every chance we get. Sigh.