Integration of emerging hydrogen-enriched compressed natural gas (HCNG) distribution network with active distribution net-work (ADN) provides huge latent flexibility on consuming re-newable energies. However, paucity of energy trading mechanism risks the stable earnings of the flexibility for both entities, especially when rising highly-efficient solid oxide fuel cells (SOFCs) are pioneered to interface gas and electricity. To fill the gap, a two-stage robust Nash bargaining strategy is pro-pose...