Is Zhu Donghui a disciple of Tianshifu?

Yes According to Baidu Encyclopedia, Zhu Donghui is a descendant of Shi Tian, a Taoist priest in Longhu Mountain. He was born in a feng shui family. Influenced by his family since childhood, he studied the essence of Feng Shui, Yijing and Taoist culture. Later, he joined Shi Tianjia in Longhu Mountain and learned the secrets of Taoism, especially good at Feng Shui, eight characters, faces and names.