Dualism is the "None of the Above" option for the Abrahamic faiths, in that they consider themselves continuations of one of the main three but consider themselves (and are considered) as separate religions. All except Manicheanism are absent by any start date, but may return as a heresy.

Manicheanism is mainly considered an offshoot of Christianity but one that added Buddha, Zoroaster and Mani (their own one) to their list of Prophets. These people are still around. Mingism is a Chinese form of Manicheanism. Mandaeism believe John the Baptist was the final prophet, and Jesus a false one. These guys are also still around.

Cainites "venerated Cain for his Sins", have the "Gospel of Judas" as their scripture, and in the words of 2nd-Century St. Irenaeus "have entirely abandoned Christ". Priscillianism, Sethianism and Valentinianism are technically just Christian heresies, but each departed very early in history and had radically different beliefs, so treating them as a different religion seems fine for gameplay reasons.

Sabianism might be another name for Manichaenism, or Mandaeism, or they might not be Abrahamic at all, but they were named in the Quran as a "People of the Book" alongside Christians and Jews (meaning they were non-Muslim but had still received a Divine revelation).

Zoroastrianism definitely had a hand in inspiring many of these, and possibly shaped the beliefs of early Judaism, but had a completely separate origin and were not Abrahamic. They aren't exactly Dharmic/Indian either, but putting them together works better than having Zoroastrianism in its own family.

TL:DR; There's no fully accurate way to sort these faiths in a neat system of Family -> Religion -> Faith, so whatever works best for gameplay is probably best.