User Groups

I would like to be able to limit access to a set of machines to a group of users.   I am currently doing this with a Whiltelist Policy applied to a Group that contains these machines.  I'm finding the process cumbersome and wanted to see if there was a better way.

It seems that for both whitelisting and for Group sharing, I have to do it on a user-by-user basis.  Is there a way I can grant permissions to a "User Group" so that I can just add new users to this group instead of having to add them individually  to computer groups and whitelists?

thanks,

Gary