Regarding Ex-parte cases of Divorce

This is regarding legal court case of my sister. In 2011 she married, and after two years of marriage, she is living separately from her husband after some family dispute. she file a DV Act case against her husband in 2013. he also filled a case regarding like he wants her back, we received summon regarding this and she received it. But due to lack of knowledge, she did not appear in court, and this case was rejected some how. after then he filed a petition for divorce and due to not appearing in court, court give ex-parte for divorce in year 2015 to him. we already filled a case of DV Act in 2013 which is continue till date. Recently, we got to know some how that court give decree of ex-parte on divorce in Dec 2015. Till jan 2017 we have no official information regarding this and never her husband declare in DV act cases's hearings that he already got divorce on ex-parte basis. In last hearing, he submitted the proof of Divorce, so we got official information regarding ex-parte divorce. then our lawyer says that we have to re open this divorce case from high court within 30 days otherwise DV Act case will become scrap. actually we dont know what to do in this case, is it possible to reopen this case. and how it will impact to my sister. actually she don't want to go back with her and don't let him go so easily without settlement. can you please help us.