Besides of speak my experience, I need to provide a solution for the following problem:, you need to indicate how you can separate users based on a configuration, that you don't know but it will change when the application user decides. This solution should consider that the selected users should be always in these selected groupp, even if the user turns off the computer or enters the next day the user still has the same group, until the configuration changes and maybe is possible that the configuration indicates that user will be in another group. Also you need to consider that the user will be not stored in any place and you cannot store it in any database. For more possible solutions I give more constraints came, making hard and difficult for the limit of the time