there is no badi available for this unfortunately to filter the EMployee groups, you need to enhance above badi or pass paramaters in the role through LPD_CUST
I would recommend to use the above badi which you found and enhance it for filtering.
Typically, you would get the employees reporting to the manager ie direct and indirect, using OADP
You can use little bit of OADP evaluation paths or the FM to get the list of empoyees you want to see too,
You can check both options.
https://wiki.sdn.sap.com/wiki/pages/viewpage.action?pageId=190743879