What is best way to purchase the property in the absence ...

Dear SSP

First if you want a legal POA  format contact any nearby advocate who is well versed in the property matter.

Secondly you need not do anything to get the property in your name because at the time of purchase of the property in the Sale Deed in place of Purchaer's name first your name will be shown and you are represented by your POA Holder who is nothing but an agent representing in your place at the time of regisration and I hope you will not give any powers to your brother or Attorney such as sale of the property, mortgaging the property, raising loan on the sale deed with private financial institutions or entering into agreement of sale, receiving advance monery etc.,  without your consent.

Thanking you,

It is not necessary that a purchaser must present at the time of registration. you can authorize a representaitve on your belaf, vide  32-A  Form (as prescribed in Registration Act) to be appended at the end of sale deed.