This series of blog posts are meant to be resources guides to complement the biographies of the great masters and scholars on the Treasury of Lives site.
The biography in the Treasury of Lives site (http://treasuryoflives.org/biographies/view/Pelgyi-Wangchuk/490), like several other sources, alludes to Kharchen Pelgyi Wangchuk possibly being Yeshe Tsogyal's brother.
However, in Yeshe Tsogyal's biography by Gyalwa Changchub and Namkhai Nyingpo which was discovered by the Terton Samten Lingpa and published in English as Lady of the Lotus-Born, Kharchen Pelgyi Wangchuk was the chieftain of one of the seven fiefdom's of Tibet's rulers, and had a vision along with his wife while "at play in the delights of love. " After this there were dreams and sometime later Yeshe Tsogyal was born.
Later, he became a disciple of Guru Rinpoche. In Naked Awareness, Karma Chagme relates how Kharchen Pelgyi Wangchuk achieved liberation. Guru Rinpoche said to him: " Palgyi Wangchuk, listen! The mind is primordially insubstantial, without anything on which to meditate. To the intellect it is ungrounded and unmodified. Let it be self-arisen and self-displaying. Dwelling in that state, you become a Buddha without rejecting the cycle of existence.' Thus Palgyi Wangchuk was liberated. "
He is also briefly discussed in the second volume of the second volume of the Treasury of Knowledge.
TBRC Reference: http://tbrc.org/#!rid=P0RK1217
Treasury of Lives Site: http://treasuryoflives.org/biographies/view/Pelgyi-Wangchuk/490