Property of my grandfather

Dear Lawyers, I need advice for the below situation. Sorry for the long paragraph 1st wife = grand mother (my mothers mother) My grandfather died in March 2015. He had two wives, with 1st wife (who is my grandmother) he had 2 daughters(1966 and 1968) and after few years he was in a relationship with another women and had a son (1978) . However he was legally not divorced to his 1st wife until 1992. In around 1985 my grandmother got a property allocated from HUDA however it was still not registered as the clearance was not done, so later my grandmother wrote a letter to HUDA authority to transfer the property to my grandfather post which the property was registered on my grand fathers name in 1995. My grandfather took 1,50,000 from his 1st wife around this period however without any agreement and later in 1997 he sold the above property (that was registered in 1995) to his 1st wife with an agreement in 100 Rs stamp paper in presence of 3 witnesses. Due to mutual agreement and since my grand mother believed my grand father she didn't register the property on her name thinking that there won't be any issues in the future. Meanwhile my grand father died in March 2015, however he didn't write any will to anyone about the above said property but surprisingly his 2nd wife and son have started asking to distribute the property into 3 (son of 2nd wife and 2 daughters of 1st wife). My grandmother had the original stamp paper signed in 1997 which we got it validated and got the house registration done in the register office with the help of a lawyer as a gift settlement to her 2 daughters in the year 2016. 2nd wife and her son got to know about this and they are asking to distribute the property among three. Now they have sent a notice too to distribute it among 4 (2nd wife and her son, 1st wife's 2 daughters) else they would file a forgery case against the 2nd wife and the 2 daughters. In 2016 they filed a civil case asking for the 1/3rd share. Now again in 2018 they have filed a FIR against my grandmother, mother, father and all of the family members and police investigated and sent the case for closure as False however I believe they still have a chance to challenge in the court Can you please advise if it is better to go ahead and deal the case in a court with the lawyer or do a settlement of dividing property into 3 (2 daughters and a son). Also will the criminal case affect my job during background checks as I am no where involved in the property?Please advise P.S: My grandmother is staying in the house since 2001 and has the electricity bills on her name since then