Board Thread:General Discussion/@comment-24679308-20140318211927/@comment-24676399-20140319014851

Kaien's body and likly his soul was still fused with that hollow bug thing that killed his wife when he died. After dieing his/that hollows soul went to Hueco Mundo where it was ate by one of the Espanda. Which is how the Expanda was able to use Kaien's shikai.

So no not the reincarnation they look alike because of being family.