Board Thread:Questions and Answers/@comment-26572409-20150704135123/@comment-10587310-20150708195210

I think all of white was passed to Ichigo when he was conceived and Isshin was sealing white away inside Ichigo. During that time white fused with Ichigo's soul reaper powers becoming Zangetsu. And that's why Isshin didn't get his powers back even after Masaki died. He was still sealing white away until he became to powerful to contain anymore. So I don't think that Karin and Yuzu have the same or similar Zangetsu's waiting to be released. If they did then wouldn't Isshin still not have his powers back. His power would still be needed to seal white in Karin and Yuzu.

But I might be wrong and that Isshin is still sealing white away and only got the power that was sealing white in Ichigo back.that might explain why he didn't use bankai when fighting Aizen. But if that is the case I doubt that the white that is in Karin and Yuzu will become Zangetsu but different spirits.

But I still think my first answer is the right answer.