Question is:
1. Whether the daughters have any right on this property?
This is a self acquired property of your grandfather who died intestate. Therefore as per the provisions of Hindu Succession act, 1956, the daughters are also entitled to an equal share in their father's property left behind by him upon his intestate death.
2. Is there a Declaration or NOC required from the daughters to execute the partition between the 3 brothers?
The daughters can relinquish their rights in the property by executing a registered release deed in favor of other share holders. This will enable the other three share holders to acquire the property and share the same among them as per their own terms in an agreed and amicable manner.
Please Note: One of the daughters is not alive and is survived only by her children who are now adults and independent)
The legal heirs of the deceased daughter are entitled to her share in there property and if they would like to execute a joint registered release deed in favor of the other share holders, this will be legally valid fort the others to acquire and enjoy the properties.