Question about requestor role to add user to a group.

How do I setup a requester role to add a user to a group without actually giving the requester access to the group?

For example
Our ADManager users have the ability to add users from their offices to different groups under their respective OUs.

Now I want the ADManager user to also be able to submit a request to have themselves or others added to the "domain admins" group.
The user is not able to see the "domain admins" group in the request to select unless I give them access to the group which means they also then have the ability to add themselves or others to the group which defeats the purpose.

How would I do this?

Thanks