Nested Groups - How to? - updated

All--

Thank you in advance for any help. Please bear with me as I've just been handed a fairly large SW environment.  Latest general release versions of all components.

UPDATE:  OK.  The act of actually writing it out solved MOST the question below.  Next, how can I find a resource that doesn't show ALL groups (at the same level) and not just "Down" groups either (see pic)

For example, I'd like to add a custom property NetEng to each object (router, switch, interface, etc..) that is appropriate, suggestions?

Original question:

A number have groups have been set up, some static, some dynamic.  No real rhyme or reason per se. Many thousands of interfaces, objects already exist.

I would really like to create groups that are nested, such as North America -> US and Canada and Mexico at the next level.  Under US -> individual states then cities then servers or hardware in those cities - you get the idea.

I am very much not seeing an easy way to represent this.  Maybe I'm thinking "groups" and I should be calling it something else.  There are a number of posts and articles on nested groups, but none of them are particularly clear on "how" to do it.  "Manage Groups" seem great for creating a bunch of first level groups.

Of course the next obvious questions are getting the many thousands of individual objects into these new groups - but we can save that until after step 1.

Thank you again for any help

NCH