After six years at the ranch, she left California to visit the Church's so-called "mecca" in Clearwater, Fla. She said Church elders asked her to remain there and become a full-fledged member of the Sea Org, while her parents remained in California.
"I wanted to go back and see them," Hill said. "And I was even about to get on a plane, and I just got pulled into a room and screamed at, telling me that, you know, I'm here to be a Sea Org member."
Hill's parents declined our request for an interview.
Hundreds of miles away and unknown at the time to Jenna Miscavige Hill, Astra Woodcraft, 29, was the daughter of Scientologists and as a child also went to Scientology schools and belonged to Sea Org. At age 15, she married a fellow Sea Org member and her days consisted of studying -- mostly Hubbard's teachings -- and clerical duties.
"I worked 15 hour days," she said. "We worked seven days a week. I maybe had only two or three days off a year."
Woodcraft said disobedience wasn't tolerated in Sea Org, and describes the reaction she says she received when she once refused an order from a higher-ranking Sea Org member.
"He held me up against the wall, screaming in my face," she said. "I remember thinking the whole time I was there … on the one hand I was raised on Scientology, I grew up in this environment, I didn't know any different, but I still it was like, this doesn't seem right."
Her father, Lawrence Woodcraft, said the family joined the Sea Org because of his wife's passion for Scientology.
"They paint an extremely rosy picture," he said. "And it sort of sucks you in. [My wife] would happily go for a year or two without seeing [her daughters]. I'm sure she missed them. Her total priority was Scientology, and clearing the planet. When I spoke to her about it, she'd say well, if I don't further the aims of Scientology, the kids won't have a future anyway. It was that level of fanaticism that drove her."
Astra Woodcraft's mother did not return "Nightline's" calls. Lawrence Woodcraft said he grew disillusioned soon after joining the Sea Org and wanted to take his children and leave the Church. But he said he felt that wasn't an option.
"You'll be declared a suppressive person, and then you'll never speak to your family again," he said.
"Suppressive person" or "SP" is Church lingo for someone who is anti-Scientology or, in their terms, "seeks to suppress any betterment activity or group."
"If you leave without permission, they declare you a suppressive person and they make your family and anyone who knows you in Scientology disconnect from you," Astra Woodcraft said.
Despite the risk of being labeled an SP, Lawrence Woodcraft left the church, and he and his wife divorced.
"I was told I couldn't see my dad anymore because he wasn't in Sea Org," Astra Woodcraft said.
Jenna Miscavige Hill also spoke about having contact with her family restricted. She said one day when she was 14 she got in trouble for chit-chatting when she was supposed to be studying. She tried to make a phone call to her parents, but she says she was prevented from doing so and even punched someone during the altercation.
"People were physically stopping me," she said. "Basically I got held down by like three people."