no lawyer is giving a correct answer on this.

My mother-in-law has 2 sons and a daughter. She purchased a property in 1983 and gave it to my husband who was the last son, in 1990 through registered uyil with witnesses she clearly mentioned, that my elder son or my daughter or her/ his descendants has no authority on this property. This property belongs to my younger son, and his descendants, and she settled some money to them. in 1994 I built a home on it. but last year my husband passed away, now my brother in law and sister-in-law are telling this is our property, we will move to court. 1.but I got my legal heir certificate, 2.Municipal corporation property registration certificate on my name, 3.Electricity bill on my name. 4.i have got all the original patta, uyil, documents etc. Now what should I do? incase if they go and file a case on me, will there be a delay in the judgment? or to be on the safer side, should I file a Declaration suite, injunction on them in the court? or any other solution is there for this?