Deanna Knox, Amanda's 21-year-old sister, told Winfrey that she struggles with being a good role model for her younger half-siblings, Ashley, 15, and Delaney, 11.
"I want to be as strong as I can, but Amanda is the best at that. She's always going to be the older sister, I'm just the substitute," said Deanna.
Deanna Knox said that her sister's arrest, trial and conviction has essentially put her life "on pause," forcing her to drop out of school and get a full-time job.
"My life has been put on hold," she said, "But it's not something I just do. My whole family does it. We're just all in a waiting period, waiting for her to come home."
Eleven-year-old Delaney told Oprah that with Amanda in Italy, her family feels incomplete.
"If I had one wish I'd want her to come home and have this never have happened," she said.
"I cry because I don't have my sister here," said Amanda's other half-sibling, 15-year-old Ashley. "I stay strong for Amanda because I know I have to."
All three girls said that they try not to cry in front of their parents because they know they worry so much about Amanda.
"I don't want my Mom or Dad to know that I'm sad because I feel like it gets them sad and makes them worry about me and they need to be worrying about Amanda and how she's doing," said Ashley.
Curt Knox and Mellas have maintained their daugther's innocence throughout her 15 month trial, and today said that they believe it was the Italian media that made the case so hard to win.
"The media blows things completely out of proportion and literally makes things up over there," said Curt Knox. "In the U.S. we're accustomed to knowing there are two sources to each story. Over there you can have anyone make up anything and they'll print it."
Curt Knox said that the media took words and phrases from Amanda's MySpace page -- like the nickname "Foxy Knoxy," which Amanda said was given to her when she was 8 years old -- out of context.
"They took [stuff on her Myspace page] and created a person that did not exist," said Amanda's father.
The Knox family has never spoken to the Kerchers, partly due to advice from their lawyers, and also because Curt Knox says that he's not sure it's a phone call "they'd like to receive."
"We still have a chance with Amanda, and they don't with their daughter," he said, adding that the conversation might be best to take place when the Kerchers are positive Amanda is innocent.
Asked by Winfrey whether there was ever a "shadow of a doubt" that their daughter is innocent, both Curt and Mellas responded, "Never."