Can i appear as an advocate of my niece in this case?

R/sir, case of my niece is pending before JMFC UMRED,Nagpur. the case is under section 12 of prevention of women from domestic violence. protection officer forwarded this case to JMFC Umred after police report and councilling by women protection cell with repeated domestic violence incidence. my niece choose me as her advocate to represent her case. which include interim relief under sec 23 of the said act. the opposition lawyer took the objection on point- that i was witness in undertaking given by her husband that not to do the domestic violence against her. this undertaking was signed by my niece and her husband( opposition party) and as a witness i signed it. both husband and wife were self identified in affidavite signed by them before executive magistrate, umred. being a local guardian, as her parents stay in satara district i as her maternal uncle asked the husband of niece to give such assurance to her of not repeating the domestic violence provided that she will not report the matter to police about that days incidence regarding the beating by him on that day. that agreement also contain that if he repeats the domestic violence again my niece will be free to report the matter to police.now the opposition advocate make the issue of this matter and file a pursis before JMFC objecting me to conduct the case of my niece.i will not appear in this case as witness of the said document as the document is itself explanatory.and both the party admit the same fact.