1. You stated that your grandfather and his brother hired 4 acres of land,
2. So, none of them are the owners of the said land,
3. Not being the owner they can not gift/sle and/or deal with the said property,
4. However, if the property was jointly purchased by both of hem then they should have partitioned the land duly demarcating it with metes and bounds,
5. No gift deed is valid till the gifted property has not been demarcated by metes and bounds,
6. However, the donee now can file a partition suit to divide and demarcate the jointly held property.