Could it have been Rosemarie?
iirc, JF released Elisabeth and her 2 sons to the upstairs after Kerstin was hospitalized (when Elisabeth was preparing to go see to her eldest daughter in response to the hospital's plea). JF told another tale to Rosemarie that their long-lost and wayward daughter had finally come home with her children. Upon looking at the obviously deprived and abused children (her own and Elisabeth's, plus perhaps having seen Kerstin before she went to the hospital), maybe something finally *clicked* for Rosemarie.
I don't necessarily get the sense that she is the tipper, but it's possible.
Another possibility: Who else might have seen the victims after they were freed from the dungeon?
ETA: I've not studied any published timeline so carefully nor have I tried to put together one of my own, but just how long was Rosemarie left alone with Elisabeth's two sons? Who might Rosemarie have called to come over to see/help? It must have been horribly shocking to witness these poor children and then to try communicating with them and tending to their needs and concerns during that time span. Were the other children in the home at all during this time? Wasn't it later in the day and even into the night, when they would typically be home?
iirc, JF released Elisabeth and her 2 sons to the upstairs after Kerstin was hospitalized (when Elisabeth was preparing to go see to her eldest daughter in response to the hospital's plea). JF told another tale to Rosemarie that their long-lost and wayward daughter had finally come home with her children. Upon looking at the obviously deprived and abused children (her own and Elisabeth's, plus perhaps having seen Kerstin before she went to the hospital), maybe something finally *clicked* for Rosemarie.
I don't necessarily get the sense that she is the tipper, but it's possible.
Another possibility: Who else might have seen the victims after they were freed from the dungeon?
ETA: I've not studied any published timeline so carefully nor have I tried to put together one of my own, but just how long was Rosemarie left alone with Elisabeth's two sons? Who might Rosemarie have called to come over to see/help? It must have been horribly shocking to witness these poor children and then to try communicating with them and tending to their needs and concerns during that time span. Were the other children in the home at all during this time? Wasn't it later in the day and even into the night, when they would typically be home?