If your not married to him there is nothing you can really do. If you are married to him and these are your stepchildren you should suggest to him that he comes up with some rules for his children so they behave.
If you have permission to speak into the children's life then you should lay down rules for the children. If you do not have permission then you can tell the father what he is doing wrong, but you will lose your relationship.
Rules for children are so important. Setting limits helps children learn how to regulate their behavior and learn that their actions have consequences.
