realistically: not believe them, this is obviously a scammer and not someone who actually has the authority to sell a disney property, no matter what identification they show me

in fantasy land where they can magically prove it: pay up and immediately release into public domain. then tell all the fans.

(then get lynched, because all new content will now be equally “canon,” from the most problematic crackfic on ao3 to the most egregious corporate cash-grab from any corporation… and other fans actually care about that and I forgor)