Sometimes the best way to deal with conundrums of jointly owned possessions is to retreat and rewrite, especially when one of the owners is represented by a pronoun.
When the owners are named, the rule is straightforward enough:
When two nouns are used to indicate common ownership, the sign of possession is placed after the second noun:
“This is a picture of John and Mary’s house.” (two people own one house)
When two nouns are used to show separate ownership, add the sign of possession to both nouns:
“John’s and Mary’s cars are in the garage.” (two people, separate cars)
These rules work with multiple owners, as long as they are all mentioned by name:
“This is a picture of Sam and Jill and John and Mary’s time-share cottage.” (All four have joint ownership of the cottage.)
“Sam’s, Jill’s, John’s, and Mary’s boats are tied to the dock.” (four separate owners of four separate boats)
Once we try to replace a name with a pronoun/possessive adjective, however, things start getting uncomfortable.
Refresher: Possessive adjectives are pronoun forms that indicate possession; they do not stand for nouns, but stand in front of nouns, like adjectives:
my house /our house
his house, her house, its house/ their house
If we change “This is a picture of John and Mary’s house” to “This is a picture of John and her house,” we invite ambiguity. Is it a picture of a house belonging to John and Mary, or a picture of John standing by some woman’s house? The usual way an English speaker would get round the problem would be to say “This is a picture of John’s and her house.” But this would break the rule that reserves the mark of possession for the last partner in the joint construction, although few speakers would fret about it.
It’s when pronouns replace both nouns in a joint possession that rewriting the sentence altogether is called for.
The following examples were taken from the media:
The Chancellor will talk about he and his wife’s relationship.
The body was found in her car at she and Kidd’s home in Harrison.
The first example is from TV. The use of he is completely out of the ballpark because he is a personal pronoun, not a possessive adjective. We don’t say, “he wife” or “he relationship.” The announcer could have avoided the problem by rephrasing the thought as “The Chancellor will talk about his relationship with his wife,” or “The Chancellor will talk about his marriage.”
The second example is from a news item about a man named Kidd who was suspected of killing his wife. Kidd’s wife had a different surname, a fact that apparently bothered the editor who changed the reporter’s original copy from “The woman’s body was found in her car at their home in Harrison” to “The body was found in her car at she and Kidd’s home in Harrison.”
As with the first example, a personal pronoun is being used in place of a possessive adjective. We can talk about “her home,” but not “she home.”
Explaining joint possession can be tricky. Take time to rephrase.