S. 158BC : Block assessment – Search and seizure – Undisclosed income — Protective assessment— Altering protective assessment of assessee without any change or development in findings recorded in second block assessment order of other company — Second block assessment order in case of assessee vitiated — Assessee proved nature and source of credit entries in bank accounts of two companies sourced from another company and its subsidiaries — Tribunal order setting aside second block assessment order of assessee justified [ S. 132 , 260A ]