Last week, Marc wrote:

How do idioms work? In particular, which of these is correct:

That seems up you and your wife’s alley.
That seems up your and your wife’s alley.

There’s no real ‘alley’, so the guidelines with respect to possession don’t apply.

The second example, “That seems up your and your wife’s alley,” is correct. In it, the possessive pronoun “your” indicates that Marc and his wife share the same interests or qualifications (their interests or qualifications are “up the same alley”), and that something of mutual interest has come to their attention (it’s up their alley”).

The first example, “That seems up you and your wife’s alley,” would never be correct, because neither “you alley” nor “you wife’s alley” makes sense.

I have never come across any rule stating that the guidelines with respect to possession don’t apply to idioms.

As always, I invite your questions and comments.

Blessings,
Tara