Possessive form for multiple owners

Question

Suppose I want to assert that the car owned by Tom is blue. That's pretty simple; I could say:

Tom's car is blue.

OK, but that is for a single owner. But suppose the car were owned by more than one person; by Tom, Dick, and Harry, say.

How would I use that same general form for multiple owners?

Would it be:

Tom's, Dick's and Harry's car is blue.

or:

Tom, Dick, and Harry's car is blue.

or what?

And then suppose I, not Harry, were the third owner.

What would then be the correct form for multiple owners, where one of them is the person making the statement?

Would it be:

Tom's, Dick's, and my car is blue.

or:

Tom, Dick, and my car is blue.

or perhaps even:

Tom's, Dick, and my car is blue.

or what?

Also: what rule(s) of grammar govern this kind of thing?

thanks.

Answer 1

One car, two owners:

• Tom and Harry's car needs repairing.

Two cars, two owners:

• Tom's car and Harry's car need repairing.

Some like: Tom's and Harry's

One car, three owners:

Tom, Dick and Harry's car needs repairing.

Three cars, three owners:

• Tom's car, Harry's car and Dick's car need repairing.

In speech, we often do this: Tom's car, Harry's and Dick's need repairing.

As for two people and a pronoun, we would generally use a different form:

- Tom and Harry's car is blue, so is mine.
- Tom's car, Harry's car and my car are blue.

Did I cover all the cases? :)

"Multiple owners": The limit one would use generally is three. three is multiple in that sense.