It would still be interesting to know what you mean by 'beyond any doubt'. Do we have anything in print by her claiming this, or film footage of her saying this? Or, as you say about RJ and John the Baptist, was this something merely claimed by someone else? In which case, did they correctly understand her? And was RJ also misunderstood?

Can we say with certainty that he wasn't a reincarnation of JtheB? How could we possibly know? As an aside, it's worth mentioning that Jesus seemed to claim, although other interpretations are possible, that JtheB was a reincarnation of Elijah. So anything is possible (although I'm obviously not saying that I believe that).