What is the plural of Chris?
Chris (plural Chrises)
When to Use Chris's. The spelling Chris's, with an additional S after the apostrophe, is a more common way to write the possessive form of Chris. Most style guides, such as the Chicago Manual of Style, recommend that you use an apostrophe and an S to create the possessive form of a singular noun.
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”).
If you are going to follow AP style, then you should use Chris' (i.e. “I am Chris' brother”). In this case, you add only an apostrophe. However, if you are going to follow the Chicago Manual of style, Microsoft Manual, or other style guides, you should uses Chris's.
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.
The possessive of Lucas — which you should never confuse with the plural — is Lucas' or Lucas's. Both of these are correct. Whether you use Lucas' or Lucas's depends on the style guide that you are employing. Example: Lucas' hair looks great.
If the compound noun (e.g., brother-in-law) is to be made plural, form the plural first (brothers-in-law), and then use the apostrophe + s. Rule 4a. If two people possess the same item, put the apostrophe + s after the second name only. Example: Cesar and Maribel's home is constructed of redwood.
Explanation: Plural words which do not end in the letter 's' have the apostrophe before the 's' when showing possession. Example: She is the children's writer; she is the people's princess. Example words: James, Wales, Paris and Dickens. Commentary: both James' birthday and James's birthday are grammatically correct.
So a safe solution is to treat singular nouns ending in S the same way you treat singulars nouns not ending in S: Form the possessive with an apostrophe and an S. Thomas's house. The important thing to remember is that Thomas is singular.
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.
Is it Jones or Jones's?
Jones = Mr. Jones's. Some people favor adding only an apostrophe to a singular noun ending in s, but if you follow the rule, you can't be wrong. If a plural noun does not end in an s, you must make it possessive by adding an apostrophe and an s: women's; children's.
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.

The “Chicago Manual of Style” says that you form the possessive of proper names ending in S the same way you handle plain-old nouns: Add apostrophe and S. The boss's house. Ross's 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.
Examples include one with a singular noun ending in “s” (“Venus's beauty”). So a name or other singular noun that ends in “s” (like “Chris”) is usually made possessive with the addition of an apostrophe plus a final “s” (as in “Chris's coat”).
Explanation: If the noun ends in "s" to form a possesive you add an apostrophe only. They are both correct.
When a name ends in “s” or another sibilant sound, we add a syllable when pronouncing the possessive form. So the possessive form of the name “Chris” is pronounced KRIS-ez—a good enough reason to retain the final “s.”
According to the nifty website Daily Writing Tips, this particular issue has a long history. For years The Chicago Manual of Style stated that “Biblical and classical” proper names such as “Moses,” “Achilles,” and “Jesus” should take an apostrophe only, not an apostrophe with an S, to form the possessive.
name. Plural. names. The plural form of name; more than one (kind of) name.
For proper names like James, AP says, add an apostrophe only: He borrowed James' car. For generics like boss, add an apostrophe plus S: He borrowed the boss's car. But there's an exception: When the word that follows begins with an S, use an apostrophe only. Hence: the boss' sister.
How do you use an apostrophe after an S?
In general, the rule is to use only an apostrophe after S with a possessive plural noun. You do not need to place anything else after the possessive apostrophe. With a singular noun, you place an apostrophe before S to show possession.
To make two nouns show separate possession, add an apostrophe and an "s" after each possessive noun. Ex: Kari's and Lynn's bikes are in excellent condition. (They each have a bike.) To make two nouns show joint possession, add an apostrophe only to the second unit.