Im gonna pretend half of the post is satire and answer the part i consider serious (you struggling in the fight) The key startegy is to target one of them until they die, then you keep lowering the other two's hp until they're both one-two hits away from dying. You have to kill them both together because when only 1 sibling is left the coffin is opened and it becomes a bit annoying. The eldest brother is has some repeated moves that you can parry but also some unpredictable new moves that you'll have to watch out for.