Hi,
As you mentioned above,a scheduled task to run the script can be considered to achieve your goal .
But for the schedule task ,the program was run at the time you scheduled ,not the time the new objects were created.
Even the for the Immediate Tasks, the scripts run as soon as each client refreshes its Group Policy. While this means the "immediate" in the Immediate Task still requires a period of time equal to your Group Policy refresh interval.
This means it is possible to add an Active Directory object to a security group via a group policy automatically, but need to wait some some for the group policy to be refreshed or at the scheduled time .
Fan