Developed an inclusive aggregation capability for the statisticsnorway/ssb-fagfunksjoner repository, enabling DataFrame aggregations across non-exclusive categories with grand totals. The all_combos_agg_inclusive function was implemented in Python using Pandas, with a focus on robust data analysis and comprehensive testing. The approach included extensive edge-case handling, particularly for category mappings and NaN values in observed versus predicted counts, ensuring accurate and flexible reporting. Subsequent refinements addressed deduplication after index resets, further enhancing data integrity. The work was supported by a thorough test suite, reflecting a methodical engineering process and attention to detail in both implementation and validation.