Schedule caste certificate

If someone wants to apply for first time Schedule Caste (SC) Certficate what document / action needed in WEst Bengal. I know one has to apply online at https://www.castcertificatewb.gov.in/. However under documents needed it is mentioned : Caste identity: One of the following documents may be accepted:- i) Caste certificate of any relatives having blood relation with the applicant from paternal side and proof of such relation (genealogical tree/ chart). ii) Copy of old land deed (prior to 1950) specifying community name in that document - iii) Any Govt. Document proving Caste identity. COMMENT - ABOVE 3 NOT AVAILABLE. PERSON WANTS TO APPLY FIRST TIME. In absence of above what other document will work ? Affidavit or Certificate from any other person will work? If yes, then who can give such certificate ?