You can only assign one location and one department to each employee, not multiple.
As a rule, when people ask for multiple locations or departments, they don’t actually want to assign multiple locations or departments to a single employee — they have a different goal. Depending on that goal, you can achieve it as follows.
1) When filtering by location or department, an employee should appear under more than one selection
You can solve this by creating user groups. Sign in to Timebutler and click Settings > User groups at the bottom left, then create a new user group, for example named “Location Munich”, and add the users. (Note: if you select the Shared user group option, other users will also have access to this group.) Now create another user group, for example “Location Dortmund”, and add the employees.
You can add an employee to multiple groups. For example, you can add an employee to both “Location Munich” and “Location Dortmund”.
As soon as you have created the groups, Timebutler automatically shows an option to filter by user group in most views (green Show filter button at the top right).
2) Users should get visibility permissions for employees assigned to two or more departments or locations
For this case, first create the user groups as described in 1). Then sign in to Timebutler as an admin and click Settings > Viewing rights at the bottom left. You can now grant visibility permissions for the user groups.
3) Multiple managers should approve the requests of one or more employees
You do not need to assign multiple departments or locations to an employee for this.
You can assign one or more managers to each user account. Read here how to assign multiple managers to employees.