Release deed

Unless the property obtained by your father was bought through the profits that arises out of the ancestral property it is considered to be his self acquired property.to my knowledge all release deeds are valid

Ancestral property can be got partitioned through Court by any of the coparcerner (including yourself).

Your father's self-acquired property (near ancestral) cannot be claimed by his brother.

Show the property documents to a local lawyer for proper analysis, guidnace and proceeding.

Query lacks clarity, going by your version, Your father had relinquished his share over ancestor property, and he had gone for self earned property. His brothers cannot claim any share in his self earned property, the property gets transferred  to his legal heirs. If they claim on the contrary the onus is on them to prove the same.

You said that;

After some years, my father earned money from business and bought agriculture land nearby ancestral properties in 1974 and it has been registered in my father name.

--You have not mentioned by that time whether your father is living in joint family or living separately.

--You said that partition done but not registered.  What does it mean. How partition done.  On while paper or bond paper or oral?

After clarifying the above I can answer your query. 

Yes.  Replies are need to the queries of Mr.Ravinder to post the replies by the experts.

My father was living seperately. Partition done among four brothers. They have wriiten in 20 Rupees bond along with witness signature but not registered.

Ravinder sir, 

Need to discuss with you regarding my quries.

Show all the documents to a local prudent lawyer and seek his/her guidance and advise.