A-Owner of property (who's name is in RSR of 1956)
B -Son of A only beneficiary of unregistered will for 15acres dated oct 1986 of A (Deceased dec 1986 when B is Minor).
C & D are married (before 1985) daughters of A. And later on in 1995 B got his name in ROR,1B of govt records.
B mortgaged and released parts of property without possession to banks and private person in 1996, 2002,2004&2014. He executed sale deed for 1 acre in 1998 and Transfered 4 acres as gift deed to wife in 2007 with possession.
Later in 2015 he sold remaining property + property gifted to his wife to X and now in 2018 I purchased land from X. Now I came to know C and D are planning to challange will and file suit of partition and B is going to be in support to his sisters C&D.
Please tell what are circumstances to face how to face successfully.