"No matter where you are, Daddy, no matter what you've done, we just want you to come home," Cummins' daughter Erica Osborne, 29, said. "We miss you so much. We're here for you, no matter what anytime, anyplace, anywhere."
Osborne's sister, Ashlee Conner, 26, said that if they could say one thing to their father, they would remind him of a Bible verse that he taught them growing up.
"There's one thing that he's reminded us for our entire life. And that's Romans 8:28, and that's 'God uses all things for the glory of those that love the Lord and are called according to his purposes,' and that means even this," Conner said.
Elizabeth has been missing since Cummins allegedly kidnapped her on March 13. Authorities are asking that anyone with information call 1-800-TBI-FIND and that anyone who sees a car with Tennessee license plate number 976-ZPT call 911.
Cummins' daughters said that, despite everything, they forgive him.
"I've already forgiven him, no matter what he did, I'm always going to be there ... You don't give up on your family," Osborne said. "Everything can be turned around, always, and be better in the end. There's always a plan. There's always a way to fix it."
Conner said, "We understand that things are different, but when you love somebody, you're always going to forgive them."
Osborne said she thinks her father is running away from his own shame more than anything.
"He wasn't running away from us. He wasn't running away from our family. He was running away from his own shame," Osborne said, adding that she thinks he did not want to "look us in the eye and feel that."
Cummins' wife, Jill Cummins, said that she has filed for divorce but told ABC News, "He was my everything. He was my best friend for 31 years."
"It was, to me, the perfect marriage," she added. "We had everything we ever wanted, two beautiful kids, beautiful grandkids, and I really truly believed that he loved me."
She continued, "The Tad that I know is not the Tad that the world is seeing now. He is a wonderful person."
Jill Cummins said they got married on her 18th birthday and said that ever since, "everything we did, we did together, which is strange for some people, but it was just the way we worked."
When the allegations surfaced that a student had seen her husband kiss Elizabeth, Jill Cummins said that he denied it to her and she thought he was being wrongfully accused.
"I had no reason not to believe him," she said. "Thirty-one years of marriage, you know? No problems, why would you not believe him?"
Jill Cummins said that she knew Elizabeth and that she and Tad Cummins would often give the teen rides to and from church.
"In fact, I called her our third daughter sometimes," Jill Cummins said.
Jill Cummins added that being thrust into spotlight has been extremely difficult for her but that she chose to speak out in the hopes of bringing Elizabeth home.
"That's not me. It was hard," she said of standing in front of all the cameras at a press conference shortly after Tad Cummins and Elizabeth disappeared. "But I knew I had to be strong and do it. For him and for Beth, because I wanted him found and I wanted him to either change his mind and come home, or I knew that would give more media exposure for more people to hear the story and see their faces and see them somewhere."
ABC News' Emily Shapiro and Eva Pilgrim contributed to this report