I have employees say emp1, emp2, emp3, emp4. And 2 users say admin and user. emp1 is linked to 'admin' and emp4 is linked to 'user'. (In the employee form, the related partner field is set). For the other 2 employees (emp2 and emp3), there is no related user set. When creating a challenge, both the employees with the related user field set (emp1 and emp4) can be selected and challenged. And for assigning badges for the successful completion of the challenge, both the emp1 and emp4 has a received badges tab showing the received badges. That is, gamification works fine with employees with a related user set.

For the employees with the related user field not set (emp2 and emp3), neither can they  be challenged, nor they have a received badges tab on the employee form. It is not possible to manually grant a badge to these employees too. When creating a challenge there is actually an option to filter the records, but only the users can be filtered (not the employees).

My question is, Is it possible to challenge the employees with no related user field set? If possible how?