Certificate from court for adding legal hairs

We have ancestral house in Nagpur, Maharashtra. The land is around 2500 Sq ft. and market price of the property is around 1 Crore.

My grandfather purchased it 1950. Initially property card had his name. After he passed away following peoples name were listed on the property card

1. My grandmother
2. My three paternal aunts
3. My father and two uncles.

In 1980 my aunts signed a release deed and their names were removed from property card.

My grandmother passed away in 1995. Now the property card has 3 entries.

1. My elder uncle
2. My father
3. My younger uncle.

My elder uncle and father passed away few years back.

My elder uncle has following legal hairs

1. My uncle's wife( Age 78 )
2. My two married cousin sisters ( Age 59 and Age 56 )
3. Two sons of elder cousin sister ( Age 30 and Age 28 )
4. Two daughters of younger cousin sister ( Age 25 and Age 22 )

My father has following legal hairs

1.  My mother ( Age 63)
2. My elder brother ( Age 40 )
3. Me (Age 36)

Now we want to sell the ancestral property. We enquired about the procedure at local municipality office. The officer told us to first get all legal hairs name on the property card and then start the procedure to sell the property. He advised us to take help of a lawyer for this as it involves getting some certificate from court/magistrate.

Now following are my questions.

1.  What certificate is needed to get legal hairs name on the property card? (Is it succession certificate?)
2. How much time generally it takes to get the certificate?
3. How much it will cost to get the required certificate? (approximately)
4. Do we need to get the certificate from Nagpur district court or we can get it from Pune court and Mumbai court ( My elder uncle’s family stays in Mumbai and we reside in Pune )
5. Is there any other simple, economical alternative way available to sell the property(like simple Power of Attorney by all legal hairs). If yes then how much it will cost?