He needs to get good legal advice. Fight fire with fire. If she’s coming at him legally, he needs to fully understand how she’s portraying him as the bad guy and why the courts are agreeing with her. Also, you point out that he has his family to take care of. Make sure you include his other kid(s) from previous relationships as his family, too, because they are. And news flash sis: if you are married to him, those kids are your family as well. Be open to hear the Baby Mama’s perspective. Be careful not to be too dismissive. Sometimes acknowledgement can go a long way.