Partition deed - unregistered.

I am planning to buy an apartment from a builder in Bangalore and had this observation when i was verifying the documents that the builder provided. I had some question. Let me try to simplify.A father has 2 sons (A and B) and 2 (C and D) daughters. The father acquires a land (3 acres) in his life time ie it is a self acquired property. The builder has provided a panchayat partition document (he calls it by this name) - it is in Kannada and is executed on a stamp paper among the 2 sons ans 2 daughters with some witnesses. Note that this document is not registered. Per this document, the 3 acres of land will be taken by the 2 sons and the 2 sisters will take cash and jewelry. This document is dated 1992. The builder also shared the judgement details of a similar case.

At a later point of time the 2 sons orally split the land among themselves where A gets 2 acres and B gets 1 acre. A sells his 2 acre land to the builder in 2002. The builder is now constructing the apartments in this piece of land -So the question is - can the two daughters (C and D) file a suit against the builder ( who bought the land from one of the sons ie A) now (i.e. in 2014)?If the daughters do decide to file a suit then will the court accept it?If the court do accept the suit then would the developer be able to defend himself and win the case in his favor? If yes, then the documents mentioned above be sufficient ie non registered partition deed and a similar judgement passed by the court.