A little grammar question about relative clauses

"the room in which you think they are"

Which of these alternatives are acceptable?

an seomra a mheasann tú ina bhfuil siad
an seomra ina measann tú a bhfuil siad
an seomra a measann tú ina bhfuil siad
an seomra ina measann tú atá siad
an seomra ina measann tú go bhfuil siad

(The first two versions I read in a book by J. McCloskey, Transformational Syntax and Model Theoretic Semantics: A Case Study in Modern Irish .
The last three versions are lacking, so they are probably even less acceptable or plain wrong.

Of course, there are more common alternatives without "ina", too.
an seomra a mheasann tú a bhfuil siad ann
an seomra a measann tú atá siad ann
an seomra a measann tú a bhfuil siad ann
an seomra a measann tú go bhfuil siad ann

As a "relatively advanced" (?), generally CO-observant learner, I would use a mheasann tú ina bhfuil siad/a bhfuil siad ann. That's how I remember it anyway, perhaps imperfectly, from GGMB. Not the kind of thing covered in basic grammar books, I suppose.

"Acceptable" I'd imagine every one of those versions can be heard somewhere in the Gaeltacht (as well as ina mheasann tú a bhfuil siad ).

For what it's worth, this is what I'd say.

All of these "a measann tú"s have got me confused, for one. What kind of 'a' doesn't lenite? Surely this isn't some kind of feminine possessive?

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ЯГОН ТОҶИК НЕСТ ИНҶО???

Well that was really embarrassing. Please disregard my previous post. I guess I wouldn't recognize an urú if it slapped me in the face

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ЯГОН ТОҶИК НЕСТ ИНҶО???