They are ungrateful children. They are unfilial children.

Nichiren states:

"All these beings are disciples of Shakyamuni Buddha. Since the various Buddhas themselves are emanations of Shakyamuni Buddha, it goes without saying that their disciples must be disciples of Shakyamuni. And of course the various decties of the sun, moon and stars, who have dwelt in the world from countless ages in the past must likewise be disciples of Shakyamuni Buddha." "(MW vol 2, Ibid, pg 152)

SGI members, on the other hand, are not disciples of Shakyamuni Buddha. They are disciples of Daisaku Ikeda. It is we alone who proudly declare that we are disciples of Shakyamuni Buddha. They, on the other hand, coopt their father's Law, steal their father's treasure, and then refuse to even recognize their father.