He cast himself as a divine prophet, officials said, interpreting the girls' dreams, claiming to speak with God and instructing them about the role of women in society.
In return, authorities said the Stoltzfus' "gifted" their oldest daughter to Kaplan.
He impregnated her twice, the first time when she was just 14.
The girls' mother soon noticed her other daughters coming and going from Kaplan's bedroom but did not object.
Instead, she also began having sex with him and later said she considered her daughters rivals for Kaplan's affection, according to authorities.
Kaplan's attorney said after the hearing that his client has maintained that he didn't have sexual relationships with the younger girls.
Several of the girls, however, previously testified that the assaults began early in childhood - officials said one of the victims was as young as 6 - and that they considered Kaplan to be their husband.
Their mother has said she knew about the sexual relationships but believed "it could be a good thing.
"Daniel and Savilla Stoltzfus were sentenced to up to seven years in prison on child endangerment charges in July.
Kaplan, who wore yellow prison garb and throughout the hearing shook his head as authorities recounted the assaults, did not say much, though he told the judge to "do what you think is right."
"I'm not sure what I can say to you honestly," he said before he was sentenced.
- AP
