Shoghi Effendi excommunicated his cousin Munib Shahid just for marrying against his wish.

“Not content with this, Ruhangiz, Shoghi Effendi's eldest sister, did not rest until she arranged another marriage between her cousin, Hasan Shahid and the granddaughter of the notorious Siyyid Ali. But in order not to degrade the family of the Master in public by announcing them all as Covenant-breakers, Shoghi Effendi acted with great patience and concealed their acts of infamy and unfaithfulness as long as he could. We see therefore long gaps between his announcements expelling certain members of the family from the Faith. For example, although the family of Mirza Jalal Shahid (the son-in-law of the Master), including his wife, had been in close association with the Covenant-breakers, and had shown defiance to Shoghi Effendi, he did not disclose their defection until years later. Only when Munib, the son of Mirza Jalal, with the approval of his parents, married the daughter of one of the enemies of the Faith, did Shoghi Effendi send the following cable to the Baha'i world in November 1944. It must be noted that Mirza Jalal was the son of the most illustrious of Baha'u'llah's apostles, the King of Martyrs.”

-Taherzadeh (The Covenant of Baha’u’llah Vol 3 p.360)