A friend of my father made his son and I brothers. What should I do? I wonder if I should discuss it with my brother. Will it be after becoming sworn?

It depends on how you feel about him. If you don't regard him as a brother in your heart, it's unnecessary. You regard him as a brother in your heart, and it makes no difference whether you become sworn or not. It's better to discuss this with eldest brother. After all, your eldest brother is also a brother and can give you advice.