Brian Stark needed to be with Amy's mother, and he wanted to be certain of the fact that no one would stand between him and his lover ever again.
So, Brian sent some of his men to take care of his brother and to make it seem like his brother had an accident.
On the night of his brother's trip, Brian Stark didn't waste a second waiting, he went straight to the mansion to see Amy's mom since he had not been able to do so for weeks. But to his surprise, Amy's mom and dad had packed their belongings, and they planned on leaving the city.
But before he could contact his men to terminate the mission because he didn't want anything to happen to his love, it was already too late.
His men informed him of their success in carrying out the job he gave them.
But there was one survivor.
Their child, Amy.
They asked if they should dispose of her as well or drop her in front of a random person's home somewhere far away from the place of the accident.