Suyuan's first husband in China sent Suyuan and her twin daughters to Kweilin to escape the invading Japanese army. When Suyuan learned the Japanese were coming to Kweilin, she fled on foot, pushing her belongings in a wheelbarrow.
Jing-mei doesn't hear the full story of what happened to her half sisters until she is grown up. In China, after Suyuan's death, Canning tells her the story of the babies. According to his version, the exhausted Suyuan was unable to find a ride as she fled from the Japanese. She laid down on the side of the road with her babies and pleaded with people to take them. When nobody did, she finally left them with money, jewelry, and photos, including a family address in Shanghai where they could be delivered for a reward. She went on. She didn't look back at them, hoping someone would find and care for them, blocking out any other possible scenario from her mind.
Suyuan felt she had no alternative but to leave her babies. It was a desperate decision. But this way, they all had a chance. Otherwise, they were all likely to die. Luckily, the babies were adopted by a childless couple living in a cave, so they fell into good hands.