There were also rumors that that the other one was Boba Fett but i doubt it because he worked for the Empire so it is most likely that Yoda was referring to Luke real sister
I’d not heard of that, do you any sources for them at the time? That sounds a curious idea.
Boba being briefly considered as being the “big baddie” for Return of the Jedi was another idea. Somewhere on here I think, with quotes from someone at Lucasfilm at that time.