Help Me Remember the Title of a Novel I Read! I Just Can't Recall It

The female lead is a daughter-in-law of the Xiao family. At the beginning, the entire Xiao family is killed in battle and falsely accused of treason. I think the male lead is the Xiao family’s adopted son? I remember him calling her sister-in-law. At that point, the female lead and the male lead gradually work together to hold the Xiao family together. The third brother was the only one who survived at the scene.