File RTI Application and seek copy of such relevant guide lines from BMC.
1. Please provide the copy of laid down norms/guidelines/directives/circulars/orders for the renovation of a flat for extension of Toilet, bathroom and kitchen.
Search website of BMC as they have prescribed RTI Application and as fee you must obtain adhesive court fee stamp fo Rs.10/- that has to be pasted on prescribed form of application.
(Before all this consult with a local engineer as to whether such permissions are required when there is no modification to main structure)