If we have several organizations to which Part - IS applies (AOC, CAMO, ATO, Simulators), who does the monitoring?

The supervision of the EASA PART-IS Regulation will be carried out by the Competent Authority that issued the approvals for the different activities of the organization. For those approvals issued by EASA, the inspection of each organization, once the Regulation is in force, will be carried out by the Unit assigned by that organization.