Names are proper nouns, which become plurals the same way that other nouns do: add the letter -s for most names (“the Johnsons,” “the Websters”) or add -es if the name ends in s or z (“the Joneses,” “the Martinezes”).
Only use an apostrophe when you want to make a name possessive. ("From The Smith's" is always wrong, but "The party is at the Smiths' house" is correct.)
Rule: To form the plural of a last name that ends with an s, add an es. To form the possessive of the plural, add an apostrophe. The Dennises are a nice family.
When making your last name plural, you don't need to add an apostrophe! The apostrophe makes the name possessive. The last letter of your last name will determine if you add an “-s” or an “-es”. If your last name ends in -s, -z, -ch, -sh, or -x, you add -es to your last name to make it plural.
You usually make family names plural by adding an “s” to the end. However, if the name ends in "s," “x,” "z," “ch,” or “sh,” you usually add an “es” instead (but there are exceptions). The plural of “mother-in-law” is “mothers-in-law.”
The plural of Jones is Joneses, ‐es being added as an indicator of the plurality of a word of which the singular form ends in s, as in dresses or messes. The apposition of the much misused apostrophe to the word Jones does not pluralize it.
When addressing an entire family use the family's last name preceded by “The.” For example, “The Smiths.” Use professional titles when appropriate. Always use professional titles when addressing members of the clergy, elected officials, doctors or those who have earned their Ph. D.
Although it may seem complicated at first, the rules of pluralizing last names are actually pretty simple, as Slate has pointed out. Unless you want to make your last name possessive, there aren't any circumstances where you would need to add an apostrophe.
Turns out, The AP Stylebook has always called for the opposite: only an apostrophe after a proper name that ends in the letter S. So not only would you write “Moses' wife,” “Achilles' heel,” and “Jesus' disciples,” you would also write “Chris' birthday” and “Jane Strauss' house.”
The apostrophe has three uses: 1) to form possessive nouns; 2) to show the omission of letters; and 3) to indicate plurals of letters, numbers, and symbols. Do not use apostrophes to form possessive pronouns (i.e. his/her computer) or noun plurals that are not possessives.
When it comes to showing possession, to make most surnames possessive, simply add an apostrophe and an “s.” Mr. Smith's car was repossessed. For showing family possession with surnames that are plural and possessive, make the name plural first by adding an “s” and then add an apostrophe to make them possessive.
Plural names are simply created using a simple addition of an -s to the end of the name. This is used to show multiple members of the same family. Possessive names are created by adding an apostrophe -s to the end of the name to show ownership of something.
Pluralizing Family Names
The rules for pluralization are simple: Use an -s if your name ends with a vowel or a voiced consonant.
To make a proper name into a plural, simply add S or ES. Mr. Smith plus Mrs. Smith equals two Smiths.
The Associated Press Stylebook recommends just an apostrophe: It's Tennessee Williams' best play. But most other authorities endorse 's: Williams's. Williams's means “belonging to Williams.” It is not the plural form of Williams. People's names become plural the way most other words do.
First, make the noun Williams into a plural: Williamses. Then add the possessive apostrophe according to the rules that gave us “the cats' tails.” That gives us “We had dinner at the Williamses' house last year.”
Commentary: both James' birthday and James's birthday are grammatically correct. Remember: it's up to you! Use the version which best matches how you would pronounce it. Use James's if you pronounce it "Jamesiz", but use James' if you pronounce it "James".
Possessives. Form the possessive case of a singular noun by adding 's (even if the word ends in s). Form the possessive case of a plural noun by adding an apostrophe after the final letter if it is an s or by adding 's if the final letter is not an s. Remember: the apostrophe never designates the plural form of a noun.
The rule that is used for 's' is that a suffix of 'es' is added to make it plural. This is the same rule that is applied to ch, sh, s, x, and z. So, the plural of the word 'Perez' is written is 'Perezes'.
If a name is singular but ends in an “s,” you always add an apostrophe after the name to show possession, but you can also add another “s” after the apostrophe if you prefer (e.g., Jess' office OR Jess's office). If the name is plural, simply add an apostrophe at the end to show possession (e.g., the Jones' new baby).
The Smiths' house — The house belonging to the family, whose surname is 'Smith'. There are multiple people in the family, so 'Smith' is plural. Since it's now plural with an 's' at the end, we simply add an apostrophe to show possession.
When signing Christmas cards or other greeting cards from the entire family, the father's name should appear first, followed by the mother's and then the children's. The children's names should be in order from oldest to youngest.
Second, a name ending in s takes only an apostrophe if the possessive form is not pronounced with an extra s. Hence: Socrates' philosophy. Saint Saens' music.
If the name ends in s, z, ch, or sh, you need to add es. That means the Davis family becomes the Davises, the French family becomes the Frenches, the Hernandez family becomes the Hernandezes, and the Glaves family becomes the Glaveses.