So...then why doesn't Namine have one. Did they just purposely not give her one because eventually her end wouldn't matter to the organization? Even DiZ could have given her one though...
Aqua? Or some other person who was able to take the purified darkness in Sora's heart and project it upon themselves? Could this also then be a possibility of what an unbirth is, and could the Xion=Aqua thing not be as far fetched as it seems, maybe BwHoPL are separate, yet parallel to POH, like Xion could be the counterpart of Namine, BwHoPL are counterparts to the POH, and...Aqua could then be the BwHoPL. As she could then project Sora's darkness on her own body and gradually change the appearance to the Xion we know.