If your crack is coming from the front=passenger side:
a. There is a 'torx' screw/bolt in the corner, it's kind of hard to see from the outside, as the roof rail is in the way. But, that could be loose. I had a similar 'rattle'/ creeking sound - tightened it up. No rattle/creek.
I had a contact at the suppliers plant - they were fielding a number of 'tech' questions about the roof..(can't do anything else, he was let go today..)
