Correction deed clarification

Hi Lawyers My family sold a property in kerala in 2012. Now, the buyer contacted us as he came accross a correction in the survey number. Myself, my mother and my sister were the selling parties involved in which me and my mother is residing in delhi right now. They are asking me to execute a power of attorney in the name of my sister who is there in kerala, so that she could carry it out (correction deed) on our behalf. They are also asking us to pay the registration fee for the same. please let me know 1. what are our roles defined in this process? 2. Are we(selling party) supposed to pay any fee? 3. if yes, what kind of fee is it?how much it comes? 4. Is there any hidden risks involved in this deed?