my immediate answer is "if you're asking this question you're probably not on the right track for actually understanding these concepts" but the more 'accurate' answer is that the DSMV does not decide who has OSDD vs DID based on these distinctions and afaik does not mention them at all. BPD is ctagrozied broadly as having secondary structual dissociation too and that's definitely not mentioned in the entry for that

I don't want to assume your intentions genuinely but I find a lot of the time focusing on these distinctions is not really helpful, having read The Haunted Self a few times. the entire book is very much full of "some people" and "typically" and "usually" that I think answering anything beyond "it's not exclusively secondary because barely anything in TSOD is exclusive" would not be accurate to the themes and premise of structural dissociation outlined in the book