Can this case be dismissed? What if the immovable property is left undisturbed, can they still claim

Dear Sir, We are a family of 5 children, father expired an year ago. Mother is the nominee for all the savings in bank held by father. And mother too has her bank deposit in her name. And few immovable property in name of father. Now 2 of the sisters have filed a case under VII,Rule,1,R/w Section,26 in the court claiming 1/6 of entire deposits including father and mother claiming mother as having mental I'll health. My mother is physically well and healthy except age related problems. Sometimes she doesn't get the right word to use in her conversations, use alternative words to express. This has been twisted as mental ill health of mother in the application. Now they have prevented mother to receive her deposits of father by writing to bank managers and made party to all the financial institution. They have included immovable property most of them are in father name, but one held in mother name too and one property in my brother name assuming the property was purchased and source from father. We do not intend to sell or divide any property. Can this case be dismissed? Can they still claim immovable property as per their wish right now(we others do not intend to sell right now)