Ok now this is kind of wierd but just look at it with an open mind. KH2 there is a lot of talk about the present being some sort of element or theme so then maybe the past is to. Could the BHK be the original key blade wielder and Sora is his reincarnation (like his soulreborn) and the memories Namie is unlocking/ restoring are those of the BHK. not much evidence but a unique idea... maybe a bit dumb though.