Hi Steve,

Yes you can make multiple blog using EasyBlog which each blog consist multiple authors as well by:
[Creating teamblogs]
1. Click EasyBlog>Team Blogs> Create a new team
You can set the member that can create a blog post inside the Blog A by setting the members OR by User Group
Refer these: http://screencast.com/t/wjvcKjRj and http://screencast.com/t/SMdVLyU5Wc

[Create a menu item for each of the blog]
1. Now you get 2 Team Blog http://screencast.com/t/bu4fKVsmxNs
2. By Creating a single menu item for each of the blog, (it now separate the blog by each of the team blog )
3. As author want to contribute a blog post in each of blog, they can choose it by click the pencil button and click on the association tab.
refer these: http://screencast.com/t/djicIdrAx and http://screencast.com/t/Cmm3rTsN