To obtain community certificate only 3 documents are essential.
1. Birth certificate of child to show that it is your child and born on so and so date and place.
2. Your community certificate to show that you belong to this community and consequetly you child will belond by birth.
3. Family card (Ration Card) to show that you are resident of the area under the taluk office.
Other documents are supplementary and can added if available.
The demand of taluk office is illegal.
File an application under the RTI asking for required documents to obtain community certificate of a child and also ask them to quote relevant provision under which they are asking.
Or
Take the matter to RDO, DRo or collector.