For legal heir certificate do all the heirs need to be present

Hi, We need to get a legal heir certificate. The heirs include my mother, brother and I. The problem is that my brother lives abroad and cannot come to India anytime soon for this. My qs are 1. Does he have to be physically present to sign on the application (or for any other part of the process)? 2. How can we proceed if he cannot come to India? Thank you very much!