I am my child's natural father, I am sponsoring him to immigrate to Canada, he was from my first marriage, now I have a second marriage, my sponsored child's natural mother also got her second marriage as well, now he is living with her natural mother and step-father in another country, my question is from the imm5406 form section A Mother and Father part, should I fill natural Father and Mother or his step-father and step-mother? I am a little bit confused about this as the instruction is not very clear, I will be much appreciated it if you can give me a response. thanks in advance.