1. If the property as gifted to your father then it becomes your father's property which cannot be sold by you during the pendency of the money recovery suit.
If it was gifted to you by your grandfather by a registered deed, then it is your own and absolute property, which cannot be attached by court for the purpose of security towards suit amount for the loan borrowed by your father.
In that case can file a revision petition before high court to set aside the orders of the trial court for attachment of the said proeprty and once the orders are set aside, you can sell the property.
2. This is a matter of trail, you can challenge their claim in the trial proceedings properly with the ability and skill of your advocate.
3. The court will not accept your request once an order has been passed in this regard.
You may have to challenge4 the trial court's order only before high court by filing a revision petition, you may discuss with your advocate and proceed if recommended
4. If the claim was barred by limitation then the court would not have accepted the case nor it would have taken the case on its file.
Since it is not barred by limitation, the case is taken up for trial.
You may first ascertain the facts through your advocate or furnish proper details if you are really interested in getting a proper opinion from this forum.