Separation

My sister and my brother in law married for past 10 year and they had a son, now my brother in law lives in US. Of course on fake asylum because he dont want to come back. My sister's in laws were very bad to her to i took her to my home. And she is with my mother for oast 1 year with her son. She doesn't want to go to court but she dont want to say with her husband who probably never gonna come back. Is there any legal way that my sister can get separation on papers from him because i know he will not sign in million years. She is young and i don't want her to be stuck in a marriage where we all know never gonna work because of long distance.( they never even registered their marriage) its just according to sikh religion.