"Who is the person standing between the two of you?"
Why isn't 两 being used for two?
There should be multiple correct answers for this, not just the exact way like this question because chinese grammar is not strict like that
I tried "這個人站在你都中間是誰？", "這個人站在你們中間是誰？", and "人站在你們中間是誰？", and have to wonder if this general structure should work. (All of the preceding answers are rejected.)
I'm also curious as to whether "站" can be used in its long form ("站立").