Child maintanence

Your sister can very well file application for maintenance in a court within the local jurisdiction where she currently resides.

Raghu,

Your sister can file a case for maintenance amount for her child before the family court at Chennai u/s 125 of Cr.P.C., she is employed in a governmental organisation/department hence she is not eligible for maintenance.  If she does not want to continue her married life with him for the reasons which she knows to be justified, she may file a divorce case also before the same family court.  If your brother in law wants to see his son, you can arrange for a meeting between the father and son or if the mother refuses such meeting ask your brother in law to file a case for custody of his child under guardian and ward act at Bangalore itself.

Application for maintanence can be filed in the place where she and the child resides u/s 125 and HMA 24 and as our women centric liars recommend under the DV act .But please note that child maintanence is co- extensive . As for her husband he has rights to visit the child even in the absence of any court order as he is the natural father.Under Gaurdians and Wards act he can apply for visitation as well as custody of the child and at any cost visitation would be granted to him .