One guy kept control of all three women and his brothers had no idea this was happening?
That's what it looks like, yes.
He apparently kept them all in separate locked rooms for the first several years, and only allowed them to mingle with each other somewhat a bit more recently, once he'd established that they were too terrified to try to escape. He apparently used to test them by claiming that he was going out and telling them not to move until he got back, but then coming back a short time later, and beating them if they'd moved. So yeah, he basically made them think that escape was hopeless, and that if they tried to escape and failed, they'd suffer greatly.
