Astus wrote:It doesn't take much to make up a lineage. One can also just say that it was a transmission from one of the buddhas, bodhisattvas or vajrasattvas.
Right, but in the case of Vajrayana you need, generally speaking, a master to disciple transmission. This is how it works in Shingon which is the extant representative of East Asian Vajrayana.
If this group could at least document their lineage and provide names of people who we could verify as actually having existed and practised at least some kind of Buddhism, it would lend credibility to their claims, though still not prove it.
I'm sceptical about a secret transmission of Vajrayana that supposedly lasted over 1000 years unknown. I've never heard or read any reference at all to such a group. That doesn't disprove its existence, but then the onus is on them to provide the proof.