NOC required from my brothers

Namaskar & Hello. Dear Sirs, My father died intestate and now my 3 brothers want to sell a plot of land in India which is our family property. They are requesting that their two sisters (my sister and me) provide them with NOCs. We want a share out of the sale but we reside abroad. Our three brothers reside in India. We are being told that to sell the property the NOC is urgently needed. 1) What we need to know is, if we sign on the NOC, would we be relinquishing our share from the proceeds of the sale? 2) How can we (the two sisters) protect our interest and make sure we get our share? To this our brothers said they would give us a letter stating that out of the sale of proceeds we will be given some money over a period of 3 years. We (the sisters) just need to be sure about this. 3) Instead of a letter from them, should we enter into a legal and binding contract? 4) How do we do that as we reside abroad? Is a trip to India needed for the signing of a contract? 5) We want to register our interest in the High Courts of India as beneficiaries of our father's property. How do we do that? 6) Is there another approach we can take to ensure our interest is secured. Please advise me on this as we are in a very big dilemma and need legal advise on this issue. Your assistance will be greatly appreciated. Thank you.