This highlights your misunderstanding. See, I'm not the head. I teach a few students. Other NGA instructors (not all of them) also teach many of these techniques. They all - if they are teaching reasonably well - are teaching the principles that are necessary to work them. Students sometimes even "discover" them on their own before they are introduced, because they are within the basic framework of principles.Then its not NGA, removing say you as head, say you died and left behind the curriclem and they didnt change it. The techniques wouldnt be taught in NGA, nor would you go into NGA to learn them if you wanted to.
And, no, having some overlapping principles doesn't make two systems the same. Judo and NGA share a large number of grappling principles. Even ignoring our striking, anyone who knows grappling wouldn't mistake one system for the other if they visited multiple classes. But that would onlly apply to someone who has an understanding of grappling. Easier if they are familiar with one of those two styles, but I think a competent wrestler would pick up some of the differences. And the same is true in a different direction for NGA and Aikido - which are more visually similar in most of our core curriulum. What differentiates systems is the difference in the principles they focus on, although there will be overlapping principles at play.