I'll write how I'm understanding this, and correct me if I'm wrong.

I know that the cat has drunk the milk, however the bird insists that it still sees it.

I want to say to the bird: "I know that the cat has drunk the milk, so how do you see it ?".

So I write:

{nIm Soppu' vIghro' 'e' vISov, chay' vaj nImvam Dalegh ?}

At this sentence, the {chay' vaj} "seems" strange, since the english goes "how in that case..", while one would expect to listen "in that case how..".

But I think, that writing {chay' vaj..} *is* the correct choice, and that the only "problem" is that the direct english translation sounds strange.

Am I right ?

vaj is an adverbial, and chay' is a question word that acts as an adverbial. I don't see that there is any obvious preferred order, going strictly by the given rules.

I'm not aware of any canon combining vaj with another adverbial or question word, so we don't have any data to go by. The best we can do is speculate.

The English can go either way: therefore in that case or in that case therefore. We can't go by the "feel" of the English when deciding about the Klingon.

Ultimately do whichever you feel is best. There is no definitive answer.

-- 
SuStel
http://trimboli.name