According to Ted Morino, the Lotus Sutra "developed" into the Human Revolution and Soka Gakkai.

Ted Morino: Even in the Lotus Sutra, the first half (from the 1st to 14th Chapter) is considered to be the theoretical teachings, but the second half (from 15th to 28th Chapters) is actual teachings and is regarded as more important. Depending upon the time and understanding of his disciples, the teachings have been changed (or developed). In other words, we have to study and understand the doctrines with open and flexible minds, not with Christian fundamentalist attitude.

Mark: That might be true regarding the major writings of Nichiren and the Gohonzon but not the Human Revolution and SGI teachings on mentor/disciple, interfaith, follow no matter what, Nichiren as True Buddha, etc. Every character of the Lotus Sutra is a golden Buddha and he asserts that the teachings are developing. Even regarding Nichiren's teachings, more than a developing Lotus Sutra, they are an explanation of that which is unconditioned, ageless, and deathless. The teachings are revealed, according to the time, not developed. That the teachings were perfect from the start is most difficult to believe and most difficult to understand. 

Nichiren in The Selection of the Time:

“Even though they did touch somewhat on this question, they did not make clear such vitally important doctrines as the ten mystic principles of the theoretical teaching and of the essential teaching, the fact that persons of the two vehicles can attain Buddhahood, the fact that the Buddha attained enlightenment countless kalpas in the past, the fact that the Lotus Sutra is the foremost of all the sutras preached in the past, present, or future, or the doctrines of the hundred worlds and thousand factors and of three thousand realms in a single moment of life.

They did no more than point a finger at the moon, as it were, or touch on some parts of the Lotus Sutra. But they said nothing at all about whether or not the process of instruction is revealed from beginning to end, whether or not the original relationship between teacher and disciple is clarified, or which teachings would lead to enlightenment and which would not.”

Ted Morino writes, “We must study and understand with open and flexible minds”. 

This is nothing more than a s[l]ick rationale for altering the teachings, deprecating the Lotus Sutra and Shakyamuni Buddha, and self agrandizing the mentor and the SGI. What he is attempting to exalt is "the inferior believing itself superior" which is one of the Fourteen Slanders.

On the other hand, Nichiren talks about pure faith as the key to understanding, not an open flexible mind. There are almost 700 references to faith and more than 400 references to mind in the writings of Nichiren Daishonin. Nowhere, not in one place, does Nichiren Daishonin associate or connect an open and flexible mind to faith. On the other hand, he teaches for example:

“The Lotus Sutra, however, contains such phrases as 'honestly discarding expedient means', 'all that you [Shakyamuni] have expounded is the truth”, 'honest and upright, gentle in intent,' and 'gentle, peaceful, honest, and upright.' Those who believe in this sutra, therefore, must have minds that are as straight and as taut as a bowstring or a carpenter’s inking line. One may call dung sandalwood, but it will not have the sandalwood’s fragrance. A liar never becomes a truthful person simply because one calls him honest. All the sutras are the Buddha’s golden teachings, his true words. When compared with the Lotus Sutra, however, they are false, flattering, abusive, or double tongued. The Lotus Sutra alone is the truth of truths. Only honest people can keep faith in this sutra, a teaching free from all falsehood. Certainly you are a woman who believes in the [Buddha’s] true words.”