In/for such requests, you should make the details clear.
It gave me a pause to choose between the two prepositions. Which one should be used? Does it have to do with the noun in the phrase? What about the following sentences?
In/for event-related questions, you should mention the details.
In/for questions about future events, you should write to me.
I find the last sentence stilted but can't put my finger on what's wrong with it. (Also, should it be "event-related" or "events-related"?)
'In' sounds wrong to me. I'd definitely use for. But ... I speak British English and I quite often disagree with what Americans think is the better preposition.
Definitely 'event-related'. It is a compound adjective. Adjectives don't have singular or plural forms; they modify nouns which do.
I wouldn't use either of the two prepositions you mention. Instead, I'd use with.
Google Books NGram Viewer also suggests that with is the most common preposition. (After that, the closest is for.)
If using just questions, with is still the most common, but the other two are essentially equal in usage:
