Please do not give the irrevocable consent unless the tenants are all satisfied about the plans. Many times in case of redevelopment, builders and others may give you plain paper designs and plans and promises but they have no meaning. While you consnet is vary valuable as the builder can file the Annexure - II and once it is filed then you may be unable to do anyhting if the builder does not do as per his promises as the promises are not registered along with the consent, In fact the consent foramt is made by the builder it self.
You as a collective tenants can insist that the Consent format be made jointly and that the builder firm gives an affidavit that they will not transfer the consent to any othe body other than the one mentioned in the consent ( Ask the builder to remaove the words - heirs/assignees, etc. - Please take help of a seasoned advocate.)
Please ensure that the consent is only to the named person and cannot be transferred. This is so because in most of the cases the builders or their agents play a game of getting consent letters from the tenants and if there are more parties involved each party will "sell" the consent letters to the other for a sum or showing that they have joined hands, etc.
The Government or the local authorities do not educate the tenants on these aspects as they are together in it for the redevlopment.
You may negotiate for all that you may wish. what the builder gives you is based on your negotiating power and the builder may be unable to give you more as his costs could be more and profits less. But the builders do not want to state these costs transparently as somtimes there are "hidden" costs or profits.
S Jadhav