They weren't raised together, no, but I figure being around one another for 50 something years would be enough time for both of them to realize they view one another as a brother & sister.

Even in an AU I can't see ByaRuki happening. I just can't get past the "but they're siblings!" mindset, haha. I think that if Hisana found Rukia when she was still alive would have been interesting, though - maybe she would have lived. I always got the feeling that Hisana didn't have the will to live because she felt so guilty.

And it's no problem! You're welcome to express your opinion on here :)