Board Thread:Questions and Answers/@comment-26572409-20150704135123/@comment-1978840-20151210015136

This is what I've interpreted: White had the ability to transfer its powers into the soul of a person. Urahara had a method to suppress a Hollow presence by connecting the polar opposite to the affected victim of Hollowfication. It wasn't until after the viewer saw the Hollow within Ichigo become dominant that we also saw Isshin return to his full power(or something close). This would imply that the ability to suppress White was no longer possible. Also, the main intent of White was to merge with the latent power of a soul, not multiple souls. If speculation is acceptable: Since the whole explanation of Ichigo's secondary abilities were passed on from his mom, it would be safe to assume that the entire presence of White was passed onto him and not his sisters as well. It would also imply that his former powers like Hollowfication(maybe, maybe not) and Fullbring were a result of the presence within his soul.