(your swap nezuko! Lets say giyu convinced sabito to let swap tanjiro live!)

During the hashira meeting (or nezuko's trial) she woke up just before it started (because of a noisy Kakushi) she saw the hashira (after the introduction of the hashiras)

She Noticed the two water hashiras, giyu Tomioka and sabito.

Giyu looked at her giving her a reassuring smile and sabito sighed "let's hope your right about this.." giyu nodded at sabito looking towards nezuko again "... If only we got there a day earlier.. Your brother wouldn't be a demon.."