That has led to another case BTW: A (out-of-wedlock) daughter suing her mother to tell her the biological father(s). Mother say no, that's private and noone else's business. Dauther say her mother is preventing her rights to inherit from the biological father.

Sooner or later there will be a similar case where the child has some illness or condition & will argue the need to know for reasons of genetics/ hereditary illness. Or where a paternal half-sibling might make a suitable bone-marrow or organ donor. I think that one will be harder to resist.