Is 7/12 Mandatory in Maharashtra !

Ghunta etc. this units were used traditionally , but now proper units are in meters
8 Ghunta = 809.36 sq. meters

To be frank myself have one  old anchestor land less than 200 sq. meters ,

your statement you  can not get independent land record for 809.36 sq. meter is not acceptable to me 
I accept there is a law Maharashtra Fragamentation and consolodiation act but 809 sq. meter is sufficient large area

Seller who has sold land to you , I feel is taking you for ride  . He can do proper partition of land and then sell the land. 

Even two different plot can be made of 400 sq. meter 

You need proffessional legal consultancy of local of advocate dealing a lot in land revenue matters. 
It seems you are investing money and saving money on proffessional which is indeed causing lot disaster in your case to large extent 
 

Please read personal message