"I looked at her, I'm like, Really?" recalled Denise. "Where did this come about?"
Within a week the emancipation of Reagan was underway. Both families went before a judge, and Reagan's parents signed an agreement to allow her to marry Evan, thus emancipating her.
In an exclusive interview with ABC News, Reagan's parents and her maternal grandmother, Diane Bailey, said they believed Reagan was manipulated by attorneys with an anti-abortion agenda, who used Reagan to publicize their cause.
"They are activists," Bailey said about the attorneys. "They want to make a sensation for themselves."
Reagan's family was frustrated, Bailey said, because no attempts at mediation were made, and Reagan's signature was legible on legal documents, revealing her identity.
"For us," Reagan's attorney, Steven Casey, told ABC News, the "lawsuit is, for lack of a better phrase, the nuclear option."
Meanwhile, Reagan was adjusting to the idea of being emancipated from her mom and dad.
"I had an idea of what emancipation was," she said. "But I never got, like, the whole gist of it."
Reagan broke off contact with her parents. She and Evan were living with his family and preparing to have the baby, due in September.
Then, in yet another surprise twist, just two weeks ago they moved out of the Burnsides' house and moved in with Reagan's mother.
"They made the choice to move back to my home," said Denise Koen. "I know we're going to have to take everything slowly, but it's such a blessing. I'm really, really pleased that she's back."
Watch the full story on "20/20: With Parents Like These" TONIGHT at 10 ET.