What should a questioner do whose name was not included in the inheritance document with his full siblings from the same mother, and is he entitled to claim his legal share of the inheritance?

The questioner has the right to claim his share of his father's inheritance if he proves his paternity with Sharia-compliant evidence. The judge must grant him his share as one of the sons. Non-registration in official documents does not prevent inheritance as long as the lineage is legally established.