Complex sentence: The family is found by Mother's "Ma" brother and they stay with his family for some time, but at insistence of his wife who is afraid of the consequences if Ung identity is discovered, they have to leave.
Split into simpler sentences: The family is found by mother's "Ma" brother and they stay with his family for some time. At insistence of the Uncle's wife, who is afraid of the consequences if Ung identity is discovered, they have to leave.