After shipment, genealogy mismatches at an ESS site accumulate less from module swaps, which are managed as genealogy events, than from BMS board (BMU/BCU) replacements, which are not recognized as genealogy events at all. Assuming annual replacement rates and record-omission rates for a 100 MWh site (99,840 cells, 1,920 modules, 240 racks), cells whose parent chain cannot be verified accumulate at 554 per year and 5,541 over 10 years (5.55% of the total), with 72.0% originating from board replacements. Module swaps account for 25.3% by event count but only 9.0% when weighted by cells. Since Article 77(7) of the EU Batteries Regulation requires repurposed and remanufactured batteries to carry a…