Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
How do we deal with non-Muslim parents when they engage in things which are forbidden?
You should show mercy to them and wish that Allah guides them and use whatever means are available to enable this. Treat them well at all times but avoid their company when they are doing things which are inappropriate or are disobeying Allah. Give them gifts and assist them in all that is permissible.