Department Admin needs to raise the Absence behalf of employee, Approver is Line Manager of Employee

Department Admin needs to raise the Absence request behalf of employee, Approver has to route to Line Manager of Employee is the expected behaviour. If Department Admin Raise the Absence Behalf of employee, and if it has to route to line manager then we dont have route through Worker's Line manager, We have only Route through Requestor Line Manager.
So is there any way we can achieve, if Department Admin raise Absence Request behalf of employee then approval has to go to Line manager of employee.