In India, it's very common to say…
"My in-laws have come these days."
This simply means that the speaker's parents in-law have come. The use of in-laws with the word 'law' pluralized is incorrect. I know that because we say sisters-in-law and not sister-in-laws to mention more than one sister-in-law.
But then…
Imagine a game wherein married couples are made to sit on one side and their parents on the other. So now, at one side there are 'coupleS' and on the other side there are 'in-lawS'.
I'm adding 's' to make 'in-law' plural the way we make other words/group plural – 80s, CEOs, MDs, scientistS, brotherS, sisterS and the like!
ONE PAIR OF PARENTS-IN-LAW + ONE PAIR OF PARENTS-IN-LAW = PARENTS-IN-LAWS?
Again, the last letter 's' is NOT pluralizing the word 'law' but indicating more than one pair of 'parents-in-law'.
Is that okay to say or write? in-lawS that way?
Best Answer
On the contrary, it's correct in the sense that in-laws originates from an abbreviation of parents-in-law (you may substitute any appropriate relation for parents here). You're right that we pluralize the noun (parent, sister, etc.) rather than the adjective. But when abbreviated, the abbreviation itself (in-laws) becomes a phrasal noun functioning grammatically as a compound noun, and we pluralize the ends of those. This usage is so common that in-law isn't even an abbreviation any more; MW, Macmillan and others list it as a noun in its own right, following the standard pluralization rules.
Your examples aren't quite analogous, because they all end with (or simply are) nouns. Instead, I'll turn to one of the prototypical American English pluralization gotchas: attorney general. This follows the same rules of plurality as parent-in-law because general is an adjective, rather than a noun, as with in-law. That means it becomes attorneys general in the plural. A common abbreviation for attorney general is AG. And if I'm speaking of more than one AG, I'm talking about multiple AGs.
No, they would still be parents-in-law (or in-laws if you omit parents). We would understand that there are multiple married couples of in-laws from the context. If you want to be explicit about it, you'll need to add a few more words; as I've done in the previous sentence, for example.
As an aside, in your game show example, we'd be likely to just say parents, because they're only in-laws to half of their respective married couple. But of course that has nothing to do with your actual question and I know it's not what you meant.