The following is with limited understanding on the matter.

For Legal representatives of the deceased Govt. Servants the applicant may approach Mandal Revenue Officer/Tehsildar and the Govt’s revenue office has placed requisite forms at the following link:

GOVERNMENT FORMS

Revenue Department 

https://www.esevaonline.com/htmlpages/government_formsnew.htm

 Application for Issue of Legal Heirs Certificate/Family Members Certificate

However you may check with concerned office and obtain correct forms and knowledge of process.

It shall be appropriate to approach a lawyer well versed with such matters and proceed under expert advice.

General public may have to approach civil court.

There are law firms and lawyer who handle such cases e.g.

LCI Expert

A V Vishal

 and

INDIAN LEGAL ADVICES - HYDERABAD

https://abgandikota.blogspot.in/2011/07/revenue-forms-of-income.html

You may check with them and finalise your terms.Your near and dear ones can also guide you to a competent lawyer handling revenue/such matters.

Thank You Mr. Kumar Doab for the response, had approched the civil court and obtain a Succession Certificate, based on this will I be able to apply / Obtain a Legal Heirship certificate? I am a private employ. please guide me in this regard.

thanks again.

Kindly contact a local lawyer and explain you  need it for which purpose.

Your lawyer shall guide you as per latest GO's and guidelines applicable to your state.