JMS looks like a very capable product and I have just two specific questions that I cannot seem to locate on your web site....

1. Can JMS be used on two existing Joomla installs?

2. Can those domains share user database so the login credentials will be the same (with CB 1.4) on both sites?

Sites
www.ccemmaus.org
www.soncoastchrysalis.org

Primary Goals is to share the user databases on these sites to simplify the login process for members.

Thanks in advance,
Chuck

1) Yes you can install Jms Multisites on an existing website and convert it as a master website.
2) It is possible to share the users with CB 1.4 between websites.
The single sign-in (remain logged between website) is also possible when using the same domain. So you can have website with different subdomain or subdirectories that use the same domain.
In your sample, the domains are different. So you can share the users but not benefit of the single sign-in.

I have the same configuration to deploy, is there any tutorial to make this configuration ?

thanks

See tutorial video 16 that explain how to replicate a website and share the users.
www.jms2win.com/en/tutorial#jms12x-16