Dispute in demarcation of land

My grandfather owned a property which was left undivided even after his death. After a few years of his death, the property got divided between his 3 sons and 7 daughters, my father being one of them. The property is residential in nature, it has a big house shared jointly by 3 sons and 2 daughters (both unmarried). All ten brothers and sisters have received one document each from the Land Reforms Dept. stating the percentage and amount of share of the land that each is entitled to. But the land has not been demarcated as to who will be getting which part of the property. Now, 2 sons and 1 daughter have extended construction adjacent to the parts of the house in which they were living. This has been done on the basis of verbal consent among themselves. The eldest son is creating problems though as he resides in the back portion of the house and he wants almost double the share that every one is entitled to. He is threatening anyone who is planning to start construction on the property that he will create some trouble and stall construction. My father wants to start new construction on the property and doesn't want any share of the old house but due to demarcation not being present he thinks that there will be legal trouble while passing the plan of the construction. Given the nature of the eldest son, any mutual consent from his part is unexpected and hence the siblings are not being able to sit down and hold a discussion regarding demarcation as he'll put forward his demand of double share again. All the other siblings are mostly on the same page regarding this except him. Is there any legal way other than a Partition Deed case through which my father can start construction on the basis of support of the rest 8 siblings? If so, then what is the process and will it be full proof from any legal dispute raised by the eldest son in the future?