Registration of apartment

Hi, My question is with regard to registration of an apartment from the builder to my name. In 2011, 3 of us( My brother, My widowed mother and myself) decided to put money with an under-construction apartment. Initial money was given to the builder by my brother(2 lakhs) and my mother (6 lakhs) and remaining money was loaned from bank to pay the installments. The builder has given money receipt in the name of 3 of us for all the money given for the builder. The sale agreement has name of each of us. Now this is possession and registration time. Personally, I would like to get the house registered in my name only to make sure there is no legal complications later (division, inheritance etc) with my brother's family in case any eventuality to my mother. I have spoken to my bother and mother regarding this and they are fine with the decision. In lieu of this, I need to compensate them for their component of the money they had invested + some additional. Bank loan is already cleared. I have 2 questions. 1. What document I should give to the builder for him to proceed with the registration with my name only? 2. Do I have to make any affidavit/ any legal paper from my brother and mother to state they have no claim in future. If so, what is the format? 3. Do i need to keep any proof to help me with tax in long term if i decide to sell it? Regards, Ranjit