Can they co-exist?

I was wondering if someone can have both DID and BPD? Say the person who has DID was beginning to merge alts or integrate, however you want to call it. Could their DID turn into BPD?

I'm really confused about it, and I hope someone can shed some light on this for me.

Some people do have a dual diagnosis of DID and borderline personality disorder. Many of these people are likely to have been misdiagnosed, and just have DID. However, Colin Ross knows his stuff and he sometimes gives a dual diagnosis. Okay, that's part of your question. The other part is this: does treatment of DID lead to borderline personality disorder? I have read a large fraction, perhaps even the majority of the literature on DID, and I have never come across even a suggestion of this ever happening to any client. So yes, DID and BPD can co-exist, but one does not lead to the other.