Rights of grand children in the grand parents property

The case in hand is that Mr. X had purchased a property out of his own earnings and died subsequently intestate. And, subsequent to his death, the Khatha of the property was registered in the name of his wife and children. Subsequently only wife of the deceased and children have sold the property through a registered deed of sale. My questions are 1.) Once the grand father dies intestate, the property of his is considered to be ancestral and accordingly grand children shall also acquire rights on the property. Is this correct ? 2.) Does the fact that Khatha was registered only in the name of Class-I legal heirs gives them absolute rights over the property, with power of alienation without the involvement of their children. (i.e. Grand children of Mr.X) 3.) Grand children of the deceased too have a share in the grand pa’s property isn’t it. ? As such the subsequent sale deed is to be executed along with them as Vendors or they appearing as consenting witness or as Confirming Party ? 4.) does the sale is invalid ? Note: the property is in Bangalore, Karnataka.