Rivalries come from an ache for validation and affirmation, from a sense of distorted fairness, self-love, guilting and blaming others.
Paul says if we come into Christ Jesus who has the birthright of the Father God, who has the spiritual blessing and the identity of the Father in heaven and the power to shape and save the world, it gives to us the same birthright. He has obtained everything for you, that you might be trying to fight for in your family already.
Jesus fought and conquered for you, the question is, do you receive Him? Jesus is our birthright!