Apostrophe with Plural Possessive Nouns
www.dailywritingtips.com › apostrophe-with-pluralJul 21, 2014 · Although many writers misuse the apostrophe in the plural possessive, the rule is quite simple, in both American and British usage: If the plural ends with -s, add an apostrophe: the boys’ kites, the knights’ chargers, General Motors’ mission statement. If the plural doesn’t end with -s, add ’s: the children’s teacher, the oxen’s yoke.