Yichud with daughter after conversion

Igros Moshe (E.H. 04:064.1): 1. Is it permitted for a father to have yichud with his biological daughter after they convert to Judaism? Those that convert with their children it is reasonable to say that there is no problem of yichud because there is no natural lust for his mother or daughter. It is irrelevant that according to halacha they are not considered relatives after conversion. Therefore is also no problem of living together with one’s mother or one’s daughter. But the situation is different regarding a brother and sister, even though there is also no natural lust but that is only because of the actions of the Men of the Great Assembly to weaken lust for relatives. Therefore there is still the possibility of pleasure and slight lust even though it is not overwhelming but yichud should only be occasionally and it is permitted to sleep in the same house at night. It is not permitted to live together permanently. The same applies to his father’s sister or mother’s sister This is true for Jews and non Jews.