Forming compound possessives with nouns and possessive pronouns can be tricky.
Take this tiny quiz, and then we'll go over the rules for forming compound possessives. (The quiz really is tiny. It's only two questions!)
1. ____________ dog dug up my garden.
a) Paul and Jackie's
b) Paul's and Jackie's
2. ______________ cat chased the dog.
a) David and my
b) David's and my
c) David and my's
Before I tell you the answers, let's check out the rules for compound possessives.
Compound Possessive Nouns
Two or More Owners Sharing Ownership
When you have two or more nouns that you're making into a compound possessive, add 's to only the last noun if the nouns are functioning as one unit.
Margo and Martha's business was booming.
This means that Margo and Martha share ownership of a booming business. Since Margo and Martha are working together at one business, we only add the 's to the last noun, Martha.
Two or More Owners With Separate Ownership
When you have two or more nouns that you are making into a compound possessive, add 's to both nouns if they are functioning separately.
Margo's and Martha's businesses were booming.
This means that Margo and Martha have separate businesses that were booming. Since they own different businesses, we add the 's to both Margo and Martha.
Compound Possessive Nouns & Pronouns
You just learned that if the possessive nouns are functioning as one unit, you should only add the 's to the last noun in the series. But what should you do if you are adding a possessive personal pronoun into the mix?!
In that case, add an 's to the noun that comes before the pronoun.
You don't have to add an 's to the pronoun because it's already possessive without the apostrophe.
Bill's and my cat ate dog food.
The car is Elizabeth's and mine.
Today is Jeremy, Catherine's, and my last day of school.
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1. a) Paul and Jackie's dog dug up my garden.
Since this dog belongs to both Paul and Jackie, the apostrophe goes only after the noun Jackie. They both share the dog, and they both share the apostrophe.
2. b) David's and my cat chased the dog.
Since this has a noun (David) and a possessive personal pronoun (my), the noun David needs to have an 's. The possessive personal pronoun my doesn't need an 's because it is already possessive.
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