I guess this would be possible by adding a field to the business objects Employee and FRS_MyItem.
Add a second filter like
- MyItem's OrgUnit = Current User's OrgUnit AND
- MyItemField (bool) = EmployeeField (bool)
Add a initialization rule on FRS_Myitem: MyItemField = true
Add a initialization rule on Employee: EmployeeField = false
By default, only the first filter will match (CreatedByRecId = CurrentUserRecId())
If you now set EmployeeField to "true", this Employee will see all his Org Unit's Incidents including the ones he created.
But is there a reason that you don't want to set up an own role?
I would rather prefer this way - you can even automate when to assign this role to users (based on any attribute or AD group etc.)