Legal Question in Landlord & Tenant Law in California

If they have never paid for anything, you don't need to serve them with anything. They are trespassers as soon as you say they are.

Mr. McCormick is entirely correct. It does not matter whether they are related to you or not. They are the same as guests who come to your home for a party and then do not want to go home. If they do not leave when you tell them to, you could call the police, although the police often do not want to get involved in such matters. Perhaps yo can tell them that for every day they stay there you are reducing the amount by $X they will get from your estate when you die. You do not have to be honest with them as to what you actually do as to your estate, but if you have other children be sure to set up a trust for your property as when you and your wife die they will try to take as much as they can.