The girl, known only by her surname, Choe, was left behind in North Korea when her parents escaped to South Korea in 2017 because they deemed it too dangerous to smuggle her with them. The Choes said they fled because of widespread famine.
"They left their daughter behind with her uncle and grandmother because the defection process was too dangerous, and they didn't want to risk her life," said Sunmi Jung, an attorney from Lawyers for Human Rights and Unification of Korea who's representing the couple. "After arriving in South Korea, they worked hard and earned enough money to bring back their daughter."
Mr. Choe delivers groceries and Mrs. Choe washes dishes at a restaurant.
Their daughter fled the North about two weeks ago, crossing into China with her uncle before being arrested in Shenyang, Liaoning. The five other North Koreans with them also are seeking asylum in the South.
Family members of all seven defectors have pleaded in front of China's embassy and the presidential offices in Seoul this week.
"During our first phone call in three years, I asked if there was anything she wanted to eat," Mrs. Choe said on Wednesday, describing a conversation with her daughter. "She told me, crying, that she doesn't want anything except to see my face as soon as possible."
At a briefing on Friday, South Korean Foreign Minister Kang Kyung-wha said Seoul officials were well aware of the situation.
"We are mobilizing all of our diplomatic resources to ensure that they are safe and they do not end up being returned to North Korea involuntarily," he said.
China previously has returned North Korean defectors, many of whom have sought refugee status in neighboring countries. In 2017, five North Korean defectors killed themselves with poison after being arrested by Chinese police, fearing a worse punishment if they were sent back, according to Radio Free Asia.
"If caught and sent back, they're most likely to face public execution or be sent to political prison camp,” Jung told ABC News. "China signed the convention relating to the Status of Refugees in 1982. They should not expel or return a refugee back to North Korea."
ABC News' Hakyung Kate Lee, Hansol Park and Sorah Choi contributed to this report.