I Became the Youngest Sister-in-law of the Ruined Reverse Harem’s Male Lead

I reincarnated into a tragic reverse harem novel with no dreams or hopes left, and for some reason, the heroine died. Before I could fully process the shock of the original story being not just broken but erased, my sisters began pairing up with the male leads. The playful and obsessive emperor fell for my mature and kind eldest sister. The stoic and strongest swordsman in the world fell for my romance-genius second sister. The flirtatious genius of the Magic Tower fell for my cynical youngest sister. Me? I’m only six years old, so having a love line would land me in serious trouble. Anyway, my sisters seemed to get along well with their partners and eventually held weddings. But then......