And one more thing please, can she have her passport on my name or on her maiden name since we haven't been legally married ? I don't want to make mistakes , thanks again

Please I need help, I am a first time Traveller and I will want to travel to the USA with my family this year. Note we are only engaged as we planned our marriage later this year, we have a son that will be one in some months. Please I will appreciate replies and opinions. Thank you and God bless you all for the good jobs here. Thanks again