You can do the following:
1. You can execute a 'Deed of Relinquishment' in respect of the flat which is 80 lacs and therefore your brother becomes the sole owner. You relinquish all your rights, title and ownership over the 80lacs worth flat;
2. In the case of 3 flats worth 65 lacs, your brother can execute three 'Deeds of Relinquishment' and therefore you become the sole owner. Your brother relinquishes his rights, title and ownership over the 3 flats;
3. Another cheapest way is to execute a 'gift deed'. Since you execute a gift deed and its to a brother there is no need to pay exorbitant stamp duty and minimal registration fees.