Transfer of ownership

We are having a land of 25 cents and a house in that which is in the name of my father.My father passed away and it been 15 years.As it is we haven't transfer the name of that land to anybody. I am having one sibling.Its a brother.As my mother decided to change the ownership of that land to both children. As per my understanding,we three have the privilege in that land as the land is owned by my father. So need to know that .can we change the ownership to three members without partitioning the land? .Or if we have changed the ownership to mine and my brother's name,how can i protect my mothers privilege in that land.Because i don't want to sale or anything happen to that land until my mom is alive. .After changing the ownership to both children,is it legal and valid that we children declare an affidavit to my mom that we are not going to trade this land without her knowledge and acceptance until she is alive. kindly let me know is there any other way to give surety to my mother for this purpose in legal? Sonia Antony