Do the homeowners sin by allowing their Christian maid to practice her religious rituals inside their home?

It is permissible for a Christian maid to practice her worship in her own room, provided she does not display it in the courtyard of the house or in front of the children, and is not allowed to celebrate her holiday in front of the family. Ibn al-Qayyim cited that a man does not prevent his Kitabi (Christian or Jewish) wife from reading her scripture if she does not raise her voice, nor from fasting or praying in his house. He also mentioned the Prophet's (peace be upon him) allowance for the delegation of Najran Christians to pray in his mosque. However, a disbelieving maid should be replaced with a Muslim one.