Share in the ancestral property

My Self Lakshmi from Bangalore ,Pls to know clarification on my Queries. My Father wrote a settlement deed in the Year 1980 before my marriage to my Brothers and His 2nd Wife.(Properties are available in Tamilnadu & Karnataka) In the Year 1984 after my marriage myself & my sister have given a Release Deed stating that , as we are married and settled , we will not interfere in his properties for sale , including My kids will not interfere legally in future..( He has not given us any Property or Money from his properties). My Father later expired in the Year 1995 , and his settlement deed wrote in the year 1980 is taken in consideration and his properties are started selling in the Year 2014 - July . We have requested for a share personally and applied legally also , now they are stating the we have given release deed in the year 1984 and we are no part of the property for selling .( Already one of the property is sold and rest other things in queue for sale ). We are insisting to give us a share , is there any chance that we can fight legally or our query can be considered any chance . Now they are asking us to sign a new release deed for all the property which is already sold and yet to sell .