1. yes,in the same family court and in th same case you can file case to visiting the child if there is such terms.
2.if the mutual divorce petition is silent on visiting the child then you can file fresh casein Pune court.
3. The welfare of the child alone is the determining factor in custody cases and emre agreement between the aprties is of no consideration in this.
4.Do come with proofs to show that the future of the child is at stake due to absence of mother and negligence of his grand parents.
You have a good case.