Whether minor or major by age, since it was purchase on his name and after becoming major he took possession of the property, it becomes the property belonging to yor grand uncle and he is the absolute owner of the property by having marketable title.
As his wife is surviving him upon his intestate death, she and her children are the legal heirs to succeed to his estates.
Your father has no rights legally in the property until a portion of property was gifted to him in the name of oral partition.
What did your father do for transferring the property allotted to him by oral partition , to transfer the same to his name through the revenue department or for mutation of the same on his name?
Without any paper or document, you cannot claim any rights in the property whether sold away or still being retained.
You may consult a local advocate who shall throw some light on the subject matter.