I want to know about kerala government order

I am working in the Revenue department in Kerala. I would like to know that , 1. by which Govt order of Kerala power was conferred to the Tahsildar for issuing Legal Heirship certificates. 2. How do we determine the legal heirs of a person ? Is there sustaining any specific law, Act, Rule or Govt Order to determine or describe the legal heirs of a particular person? 3. Is it an illegal action if the Tahsildar excludes the name of an 8 year old person from the legal Heirship certificate of another person, if the Tahsildar receives a written request seeking the Tahsildar to exclude his name from the legal Heirship certificates of another person. Pls advise. .. TOMS.P.A Revenue department of Kerala