It belongs to the in-law

[JunO]

What would be the possessive? Since the plural, for example, is sons-in-law, then wouldn't the possessive be son's-in-law? But that just sounds awkward (Her son's-in-law office).

I came across this today in a cutline and wrote around it (the office of her son-in-law). But I'm still curious.

[fev]

I don't think there's any "rule" that would make it "son's-in-law office," and you could probably find plenty of thoroughly standard examples in which the whole NP is possessive even when the countable noun is on the left: It's "attorneys general," but "attorney general's office" (not "attorney's general office").

[editer]

The tricky part is the plural possessive. "attorneys general's"?

"It belongs to the attorney general and the other ones."

[Powderhorn]

I don't see where the possessive of the plural of "attorney general" would be awkward to write around. "Attorneys general's" is akin to talking about the blue's coats buttons (instead of "blue coats'") -- ascribing the possessive to the adjective? (Due respect intended.)

To the original question: No one would trip over talking about the son-in-law's possessions. I'm too tired to look it up, but there was a good discussion along these lines about how no one would say RsBI, even though they're the runs that are plural. Here, son-in-law is a cohesive thought as a noun, and tacking the 's at the end of it makes sense.