To assign employees to multiple organizational units, you need to assign them directly to different organizational objects. This can be done by creating positions that incorporate the organizational units and then assigning the employees to those positions. The Primary flag in the organization unit is used to indicate the main organizational unit for an employee or a manager, but it does not prevent them from being assigned to other organizational units. Acquiring an additional license for the required add-on is not relevant for this scenario. Assigning the employee at company level is not sufficient to assign them to multiple organizational units, as the company level is the root of the organizational structure and does not reflect the specific functions or teams of the employees. References = Setting Up a Service Organization, Create an Org Unit