Subclient and security groups

Need some help with a use case. We have separate help desk for different areas. The file share we are backing up has acl’s’ that allow each specific help desk access to their respect share\folders. I have different sub clients for each share and the corresponding help desk group assigned to the sub client security but i get an error stating the user does not have overwrite on restore unless I put it on the actual server security. Any thoughts would be helpful