The MHADA Buildings as per DCR 33(5) eligible for aditional FSI. Recently the Govt of Maharastra brought in Revised Noms on 3rd july 2017 wherein the Fsi is Proposeed to be up to 4.00 for Plots more than 4000 smts and on roads more than 18mtrs. And up to 3.00 for plots less than 4000 smts.
I admire your society has a strict no grill policy. For any full height window you essentially need protection for children, which can be achieved by simple railings up to about 36" to 42", made out of steel/ wood/aluminim/ glass depending upon overall decor and budget. A gap between railing and window of about 6" will also help in creating space for curtains and discourages children to lean over.