There is more option to deal with girl, but some them are class specific and some depend on your attributes and skills.
As cipher you can wipe girls mind somewhat clean so that she don't remember that his father sexually abuse her and you can convince her to go back to him or you can tell her truth or something else.
With high enough lore and intellect you can understand what is going in the ritual, which gives you more options
You can let cultist finish with ritual and let girl go back to her Lord father as double agent (then you can reveal that fact to Lord so that he can decide what