For now, there is no relation between the tables. In the Performance table, I have 1 record per user. In the Operations table, I have an Assigned To field that is a List-User field type. This is a specific type of user-related fields where you can select several users simultaneously (not one user per operation based on the users in the performance table). The List-User fields do not have record picker and display only the user names (comparing to the situation where you can use some report in record picker to display more information). The users are actual users who use the system.