Tulku Urgyen Rinpoche's third son was born to a close attendent of the Tsurphu Khandro, the great dakini of Tsurphu, and for many years he has worked as the general secretary of Tenga Rinpoche of Benchen monastery at Swayambhu, a great lama of the Kagyu lineage whose monastery in Tulku Urgyen's homeland . This monastery, Benchen, is also the seat of the illustrious Sangye Nyenpa, Traleg, and Chimey tulkus.
More about Tenga Rinpoche: http://www.rangjung.com/authors/Tenga_Rinpoche.htm
Tulku Urgyen's fourth son is Orgyen Jigmey. He was left behind in Tibet under the cultural revolution and has since decided to remain a layman.