This report delves into the role of distribution systems in the flexibility needs assessments (FNAs) that will be part of national and pan-European assessments by 2026, as stated in the recently adopted Electricity Market Design Regulation. Transmission System Operators (TSOs) and Distribution System Operators (DSOs) need to jointly work on defining the methodology and facilitating the provision of future FNAs. This report focusses on distribution side, highlighting the elements needed for such assessments and key concepts that could help to profile a methodology. The analysis explores three primary approaches of TSO and DSO interactions: bottom-up (DSO needs), top-down (TSO needs), and a combined hybrid model. The bottom-up approach emphasizes local flexibility through microgrids, demand response, and energy storage, while the top-down approach addresses the broader transmission system needs. The hybrid model integrates both perspectives, promoting bi-directional data sharing between DSOs and TSOs to manage flexibility across the entire grid. The report concludes that the hybrid model offers the most comprehensive solution, balancing local and national flexibility demands, and calls for regulatory frameworks that promote standardization, protocol development, and enhanced coordination between system operators.