You can add a user into a group using active directory users and computer (ADUC) mmc snap in or by executing a single PowerShell cmdlet.
In this article, we’ll look into adding a member to the AD group using PowerShell.
Add User to Group with PowerShell
Step 1. Open PowerShell with elevated privileges.
Step 2. Execute the following command.
Add-ADGroupMember <Group name> <user 01, user 02, user 03>