Regarding Flat Accusation from Builder or Promoter

My Father and his two Friends Purchased a Land together( whether the Porcha is in Processing to Convert my father and his Friends name, Municipality Tax Process done) and gave to Develop Building to a Builder or Promoter with an Agreement that The Builder will Develop 4 Stored Building with Two Flats per Floor. The Developer can Sell Those Flats and have to Give in Free 3 Flats each to my father and his two Friends.Rest of Flats he can sell and Those flats can't Claim by us (Father and 2 Friends). Now total Building have Completed, builder has handed over 3 Flats each to us as per Agreement. Other Flats are soled by the Builder. Now my Question is that, will we have to Re-registry 3 Flats each Per person's name? will we have Re- apply for Fresh Porcha and Municipality Tax? how can my father get 1 Flat out of 3 Flats Legally with Proper Documents. what will be the Procedure if i want to Sell my Father's Flat in Future with Clear Documents. please Give some advice as now it is very Serious Issue. you can send mail also in