I see this forum is for mutli sites but I have a question about 1 sign in for mutliple sites. I tried to send a message from front end but it kept saying error.
I am curious if I do not use mutli sites but just the multi site log in will it work with sub domains that are not in sub directories. My sites have seperate data bases but still have the same data base value.

Can I still use the single login to access these sites with out using the multi sites to share content.

Hope I worded this right

yes it is possible to use our "Single Sign-In for domains" extension without JMS.
www.jms2win.com/en/joomla-multisite?page...51&category_id=1

The requirement is that you share the Joomla mysql tables for the #__user% and #__sessions
JMS can help you doing such kind of sharing.

When using different domain on the same DB & same prefix then, by definition the content is shared and therefore the SSI for domain does not require addition sharing.

When you want remain logged when you change of domain on a same domain, then the SSI for domains is not required. You have to setup the Joomla global configuration - Cookie domains.
Again, the requirement to make it works is to share the Joomla MySQL tables #__user%, #__sessions