Thanks for the info!
This has been a lot of muddling.
What I figured out is this.
Begin by opening my eyes.
Be sure to click the:
"Add user to my blog as a contributor" below the other info for inviting someone.
On wordpress.com signup page:
Be sure to tell the others that they only need to click the "Sign up for just a username" if they do not want their own blog.
Man this has been more difficult then I first thought. It seems my eyes were just not noticing the Sign up for just a username.
WordPress could make it so that one just skips filling in blog address without having to go to another page (or have both). If someone forgets to fill in the blog address they could just write a popup dialog box asking if the person wants to skip creating a blog.
Have a great day!