The concept of JMS is based on the sharing.
- Sharing of the same joomla application (php code)
- Sharing of the content of a limited number of extensions
See the list of extensions defined in the JMS Tools menu.
www.jms2win.com/en/list-of-extensions?vi...id=269&Itemid=53
The sharing of the content of the extension is based on the sharing of the MySQL tables used by this extension.
So if you want to share the content between websites, you need to check for which extension you want to do that because all extensions can not have their content shared.
For the joomla articles, you need the "Article Sharing for JMS".
The sharing of the content of an extension is something that is decided when you create the websites.
In most cases, when you share the content of an extension, you also need to share the users.
Therefore, you may also need the "Partial User Sharing" to avoid providing the same permission to all the user in all the website.
With the "Partial User Sharing", you will be able to have different ACL depending on the websites and avoid that some users have the access to the other websites.
www.jms2win.com/en/joomla-multisite?page...63&category_id=1
Now your title say something else as you mentioned Single Sign In that does not mean sharing content.
The Single Sign-In just need to share the Joomla users to make it works.
So if you just need that, you can use JMS basic to share the users as show in the tutorial video 16
www.jms2win.com/en/tutorial#jms12x-16
and use the SSI for domain extension to remain logged when you change of domains.
www.jms2win.com/en/joomla-multisite?page...51&category_id=1