How can I make all the tasks of employees to their immediate head (to the one who is reporting to)

How can I make all the tasks of employees to their immediate head (to the one who is reporting to)

for example,
I have an employee a with employees b,c,d reporting to a , then all the tasks alloted to b,c,d should be visible to a to achieve this now I need to assign each task to both of them i.e.,the employee who is alloted to and his reporting head,is their any way to modify through ‘reporting to’ option in Employee.

If you add a custom link field with b,c,d with value ‘a’ you must be able to achieve the desired permissions using user permissions