John Davies subsection b. sets a time limit of 4 years against someone who directly aided in the abuse. The time starts to run when the victim turns 18 or when the person first recognizes that the abuse has caused harm.
It seems like you have a case against your ex, or rarther your daughter has, for directly aiding the abuse, since he knew your father was an abuser but still went behind your back and allowed contact.
The infuriating thing is that you and I both know that your ex would never have allowed such contact had he, and your parents, not been Jehovah's Witnesses. The brainwashing makes them see a jw mass murderer as a more trust worthy person than a worldly charity worker. In that sense it *is* the fsult of the WTBTS that he allowed contact, but I guess Zalkein knows best. Im very sorry. Unless the abuse happened at, say, a book study I guess there is not much to be done against wtbts.