Three of the Letters of the Living were family members

Mullá Husayn Bushrú’í (c. 1814–49): the first to declare his belief in the Báb (in Shiraz on 23 May 1844). He was given the title Bábu’l-Báb (Gate of the Gate) by the Báb. He was killed on 2 February 1849 at Fort Tabarsi.

Mullá Husayn’s younger brother, Mírzá Muhammad Hasan Bushrú’í (d. 1849). He accompanied Mullá Husayn on his travels and became badly wounded in Fort Tabarsi at the same time that his brother was killed. According to some accounts, he then served as leader of the Bábí forces and was subsequently killed at Shaykh Tabarsí.

Mulla Husay’s nephew, Mírzá Muhammad Báqir Bushrú’í (d. 1849). He is reported to have led the forces at Shaykh Tabarsí after his uncle Mullá Mírzá Muhammad Hasan was wounded. He was subsequently killed at Shaykh Tabarsí. 

(Adapted from The Baha’i Encyclopedia Project site)