Apparatus, method and program for maintaining common data in first, second and third datasets in first, second and third respective computer systems. The first computer system is assigned a sole right to approve updates of the common data while able, and a second computer system is assigned a right to approve updates of the common data when the first computer system is unable. The third computer system subsequently makes a request to the first computer system to update the common data, and in response, the first computer system updates the common data in the first dataset and advises the second and third computer systems to make a corresponding update to their second and third datasets, respectively.