Unncessarily being dragged

My sister lives in Mumbai and his son got married in Jan 2011. The lady stayed with the family for about 3 months and then deserted them due to constant fights between the couple. Over the 3 years, there had been numerous meetings to set things right but nothing worked out. My sister then sent a legal notice for either coming back and staying with them else, file for a mutual divorce. This notice wasnt accepted by their family which lives in Vizag. On 30th June 2014, the girls father came with a police man to my place of work in Vizag and took me to the police station and under pressure made me sign a letter which said that i will get my sister and her family to vizag for a meeting with them. They arent ready to come to Vizag unless they are ready with some petitions they want to file certain petitions. I did speak to a local lawyer and he is trying to get in the details of the complaint the girl's family has lodged with the mahila police. however, i am really worried that without any involvement of mine, they may come again on 15/july Can you please suggest your opinion?