Majdeddin bin Moussa Irani (before 1945 -1955), usually known to Baha’is as Mirza Majdi’d-Din, was a nephew and son-in-law of Baha’u’llah. He was the son of Baha’u’llah’s brother Moussa, known as Aqay-i- Kalim, who was a strong supporter of the Baha’i cause.
He was married to his cousin Samadiyya, the second daughter of Baha’u’llah. Majdeddin Irani was one of the inner circle of Baha’is until Baha’u’llah’s passing, and is reported to have been given the honor of reading Baha’u’llah’s will to a group of relatives and important believers.
Later, he became one of the most significant opponents of ‘Abdu’l-Baha and sided with Mohammed Ali Bahai in the schism. He lived to be over 100 years old and continued to support Unitarian Baha’ism until the end.
Reference:- ‘A Lost History Of The Baha’i Faith’