Settlement before partition of joint agricultural land

Please advice if this is legally permissible: An acre of land is jointly owned by father, mother and 2 sons (each owns 1/4 share). The father dies intestate. There are 5 legal heirs - mother, 2 sons and 2 daughters. After death of father, no legal heir certificate or succession certificate has been obtained. At this time one of the sons makes a settlement of his 1/4 share in the mentioned land to his son via a settlement deed. Is this settlement deed valid given that the original owners (3 members) have yet to partition the property? Also the portion of the late father has not been settled/partitioned. The new settlement deed between one son and his son simply states the entire property and mentions 1/4 share to be transferred. Please advice. Property in TN