Is there a legitimate Islamic way to prevent our father from transferring the ownership of his properties to his wife, or to prove our right to inheritance before his death?

If the father is in full possession of his mental faculties, he has absolute freedom to dispose of his wealth, and no one can prevent him. It is recommended to advise him not to register most of his properties in the name of the new wife. One can seek the help of a close, righteous friend to offer advice. However, if he has become senile and his mind has deteriorated due to old age, please refer to Fatwa No. 39056 to learn how to deal with him.