Darla is Theresa Burke's sister.
When Theresa's husband went missing, Darla stayed with her during an afternoon. While they were watching the weather forecast, Theresa turned off the TV, declaring that she was going to Boise to find Ethan. Her sister asked her if she was going to leave in that moment, but Theresa said that she would go in the morning. When Theresa declared that if Ethan wasn't dead and he had left his family, she was going to kill him herself, Darla asked how could she help. Theresa said that she could stay with Ben, but the boy, who was listening to their conversation, declared that he would go with his mother.
Darla heard how Theresa tried reasoning with her son about staying since he had school, but ultimately, Ben went with Theresa.
It is more then likely she was not saved by David Pilcher and lived her life without her sister and her family until she died in the old world.