I'm having a hard time finding out what the grammar is when we want to use "or" and possessive. If, for example, I want to refer to the information of a person or an organization, do I say, "that person or organization's information," or, "that person's or organization's information."
Please collect that person or organization's information on the appropriate form.
Please collect that person's or organization's information on the appropriate form.
I have looked and looked on the internet at various grammar sites. There are plenty that address the situation when there's a compound possession (i.e., when "and" is used), but none I can find that address the situation when it's not but rather is the possession of one or the other.
On this site, I felt hope when I found the following question:
But then I saw it was wrongly closed as off-topic, saying it should be for the English Learner's site. I'm not an English Learner. It's a legitimate question.
Now, that question does offer one answer, but that answer is obviously wrong because it calls "John or Mary" a noun phrase, which is a phrase that serves as a noun, when it is not a noun phrase but is two distinct nouns conjoined by "or."
When we say "John and Mary's," that's compound possession, which indicates that John and Mary collectively share whatever it is, but when we say "John's and Mary's" that's not compound possession as it indicates that John and Mary each own the ensuing noun, so if the ensuing noun were "information," then it would refer to John's information and Mary's information, like John's address and Mary's address, which may not be the same.
From this, we know that the presence of a conjunction doesn't necessarily indicate compound possession, and when the conjunction is "or," it certainly seems that it wouldn't because "or" specifically indicates one or the other and not both, but therein lies the rub because it makes sense in my head to say "John's or Mary's" or "that person's or organization's," but what sounds right to my ear is "John or Mary's" and "that person or organization's," which is why I'm seeking an answer, an answer I haven't been able to find and hope someone here can definitively provide with some grammar source material that specifically addresses the possessive case with "or" rather than only addressing "and."