Looking for a Good Quick Transmigration Novel, With One Arc Possibly Called Siblings

In one world, the male lead is the son of the heroine's father's comrade-in-arms. After his father dies in action, the heroine's parents bring him home and raise him as their own son. One day, when he's grown up, he accidentally overhears that he isn't their biological child. He starts falling for his adoptive sister, but her father disapproves.