Variation of land size in property papers, please advise what to do ?

I have house built in my place in 2300 square foot (1200 construct + 1100 free space)which is near about 40 years old and now I want to build it again as it is old construction.when I went to bhumi abhi lekh office I found that there is only 1065 square foot land is on my father's property card. When I check sales deed it contain whole 2300 square foot land and sales agreement has seal of sub registrar office. Now dispute arise when I start to demolishing old house one person come to me and said this land is not yours and start to threaten me about stay order from court . The land beside my plot is of 10000 squarefoot and is under court matter as 17 persons claiming their ownership ;the person who threaten me is one of them and in city survey whole land is on his name. So If I want to get clear about ownership where should I consult as my father was dead their is no one who can give me clear idea about the actual matter.