1. The property was purchased on the names of your grandfather and your father.
Therefore as legal heirs to your father's share in it, you, your siblings, your mother and your grandmother shall become class I legal heirs to your deceased father to succeed huis share in the property. This share of property exclusively belonged to your father, i.e., half of the property.
Now the second half which was on your deceased grandfather's name again devolves on his own legal heirs, your father is one of the class I legal heirs to your deceased grandfather along with his own siblings and mother.
Thus your father's share shall again devolve on you, your siblings, your mother and your grandmother.
Therefore your father's sister being one of the class I legal heirs to her father, is entitled to one share as a lawful right.
2. DKT or Darakastu land is a wasteland assigned to the poor and downtrodden people of the state in Andhra Pradesh. The state government assigns land to poor people who do not have enough resources. This land is assigned for cultivation purposes only and no transaction such as sale or buying can happen on this land.
The assignee cannot sell this land to anyone. He/she can only return the land to the government after producing their income certificates. Sale of DKT lands is illegal as per rules in force. However, they can be transferred to legal heir. The Chief Commissioner of Land Administration (CCLA) also expressed the view that the lands assigned to the poor and landless prior to 18.6.954 would not attract the rule prohibiting the transfer of lands.