How to pluralize last names that end in S or Z, advice from the NYT

“Anyone who tells you there are universal rules to how to add an apostrophe ending in S is either wrong or lying,” Jeffrey Barg, a grammar columnist, said to The New York Times in a recent article. "You can’t be wrong as long as you’re consistent."

"The Associated Press Stylebook, widely considered to be the gold standard among news organizations, is clear on its rule for the possessive of singular proper names ending in S — only an apostrophe is needed (Harris’), though there are always exceptions. The New York Times, The Washington Post and The Wall Street Journal all do the opposite, opting for ’s to mark a singular possessive and a simple apostrophe for plural possessive (Harrises’ and Walzes’)."

"Merriam-Webster, the oldest dictionary publisher in America, splits the difference: For names ending in an S or Z sound, you can add ’s or just an apostrophe, though the dictionary says ’s is the more common choice.”

-- Remy Tumin, breaking news reporter at The New York Times, excerpt from "Is it Harris’ or Harris’s? Add a Walz, and it’s even trickier." (New York Times)