I am working with a client on a website and he has submitted the text below which I believe is not written correctly. Although we know that there are five boroughs in NYC, it seems the five boroughs are also related to Nassau, Suffolk and Westchester. I have corrected it by adding "as well as" after "City of New York" but my client has asked me to use the original text. Is there a rule or clear explanation that I can cite to clearly explain why this is not the best sentence structure? Also, what is the term for the phrase "as well as" that separates the nouns after the preposition?
Text in Question: "We have appeared for decades in the five boroughs of the City of New York, Nassau, Suffolk and Westchester Counties"