I have had a lot of interest to this plot and would like to suggest a variation.
The member of staff will become a close personal friend/family member who is now lodging/staying at the family home due to a run of bad luck caused by the father/husband.
While staying he abuses his hospitality and corrupts the wife/daughter right under the nose of his nemesis.
For some reason the girl remains quiet even after the corruption and even enjoys it after a time.
I would imagine a lot of silent rape scenes with a risk of being caught, interupted or even heard. Molestation and impregnation.