Bigamy & domestic violence and bringing illegally weded wife home

My sister had been married for 25 yrs. Child less. She has always been subject to donestic violence. Not supported at all. Last yr husband court married another girl. FIR lodged with other details. Since then she is living with us. charge sheet has been sent to court in Dec 2018. Proceedings not begun till now. We also filed for alimony.. hearing soon. He has been charged under sec 494, 504, 506, 498A and 3/4 DP act. He lost a lot of money to save himself frm police.. under pressure..he wanted to compromise.. but keeps changing his statement. Now.. he has also brought the girl home since last one month. Plz let me know... 1. If anything can be proceeded with for bringing illegally weded girl home.. 2. What could be our conditions of settlement.. in case we proceed and hiw it can be proceeded with.. so that we are safe in future.. however i find it very unsafe for my sister to return to him and more so now. 3. Criminal case hearing has not started in 1 yr.. can nyting b done