You always make odd sentence and then ask query about some of it exerting unexpected illogical result.
because we have no way to form some questions due to very limited context of the sentence you offer.
but in order to meet your "aim", we have to just write such questions some of which have nothing to do with your original.
We meet Nimue as she rides her horse along an idyllic grassy hill.→
We met a woman who was riding a/her horse along an idyllic grassy hill, she is Nimuse.
1.Whom /Who did you meet who was riding a horse along an idyllic grassy hill? and what is her name?
2.Along where was Nimue riding her horse when we met her?
Where did you meet Nimue as she was riding her horse along an idyllic grassy hill?
3.When did you meet Nimue as she ……hill.???
4. Why did you meet Nimue as she……hill?
Why was Nimue riding her horse along…hill when we met her?
(ridiculous question due to the context)
5.Which woman did we meet as Nimue
was……hill?(ridiculous question to the sentence)
6.How did we meet her as she …… hill?(ridiculous question to the sentence)
you can just put all of interrogative adverbs together to form a question:
8.where, when, why and how did we meet Nimue as she riding……hill?
but you have to form different questions by using of different interrogative pronouns(who, what which)
remember we have no way to write such question as in this situation:
But ''How'' can not help to elicit such a response as the "third", for "Jefferson was the third president", where English has no really satisfactory way of phrasing question.
(in such case as above we have no way to form question)