Board Thread:Naruto Discussions/@comment-25847976-20141218061108/@comment-5407586-20141218070130

It was stated in the fourth databook that the Gentle Step Twin Lion Fists is a high-level secret technique taught only to the Main Family of the Hyuga Clan; only in the anime Hinata is the creator of it. Hiashi didn't show it onscreen, yes. And Hinata not being the heiress doesn't mean she has become a Branch House member: see the last point for more info.