There is a way but it's probably not the correct way of doing this and could break your server
You can change the group permission on your users folder to admin (or any other user/group) by typing at a command prompt
chown -R <username of user>:<username/groupname of user/group to be given permission> foldername
for example i've just created a test user so I connected to my server by SSH and typed
cd /home/e-smith/files/users
chown -R test:admin test
You then need to give the group permission read/write & possible execute
chmod -R 770 test
If I now type ls -l I can see that for my test user's folder test is still the owner, admin is the group, test still has w/r/e permissions and admin also has w/r/e permissions.
If I now type \\<servername>\test I can see test user's files, create files in test's folder, delete files and move files.
Again I don't know what else this will do to permissions so I would test this until you are sure that it hasn't broken something else. i.e email, user backups, password changes e.t.c