SharePoint 2010 - Use a Subsite's Permissions Group at the Parent Level

Question

Is it possible to use a permissions group created at the subsite level as a group at the parent level? As an example, I have a parent site and a subsite. The subsite uses a locally maintained group (Subsite Users), but I want to use this same group at the parent level so that maintaining one level keeps the other level up to date. I want to keep the group maintenance at the subsite level because the admins who will maintain the group won't have edit permissions at the parent level.

In the end, the structure should be like this:

Parent site: Subsite Users members have Read permissions at this level.

Subsite: Subsite Users members have Contribute permissions at this level, and admins of this site have the ability to maintain this list.

Answer 1

This isn't the best possible answer since it doesn't completely address the question I asked above, but in my particular case I was able to provide access to All Authenticated Users at the parent level. The final permissions structure is:

Parent site: All Authenticated Users has Read permissions. Everyone with the ability to get to the site has access to the page's contents. Furthermore, this is an AD group, so it's maintained at the farm admin level and will always be up to date with all authorized users.

Subsite: Subsite Users group has Contribute permissions. Local admins maintain this list.

Again, this approach doesn't answer my question, but I want to share the approach in case it's of use to anyone in the future.

If anyone has a way to handle the original situation, I'd still love to know how to do it.