Partition of building consists of 3 and half storied

My father costruct a house on 80 square yard plot in Delhi in 1973(2storey) He died in 1982 leaving behind 3 sons and my mother.Proprty mutated in name of my mother and 3 brothers including me. I am the eldest son. The my mother also died in1985.Now till date property is undivided. Youngest brother is living on second floor during last 5 years. One younger brother is living in another city.Younger brother was living on ground floor and he have occupied that floor till date. I was living in First floor and have the key of First floor and also living in another city. My youngest brother want Second floor with roofright and one younger brother want ground.Electricity connection,water connection and property tax still in my father's name.Water underground sump of 5x5x5 feet also constructed on varandah ground floor connected through water connection.Overhead PVC tank of approximate 2000 litres capacity placed on top floor roof through which water comes in entire all 3 floors.Now we want to divide it among all three brothers.Please advise how we divide it by Safeway measures like right of passage through Staircase from ground floor to top floor roof,placing of Water tank on roof and underground sump should be as it .Please send me the model format of Family settlement deed and partition deed by keeping above mentioned points