How can I explain what I want to achieve, I will try (english is not my native language)

I have A master site, that is fully operational, up and running. I want to create slaves directly inherited from the master site, and have the user tables shared (Login from the master OR one of the slaves logs you in on all sites, master and slaves). This can and must be achieved by using templates, so I have read.

How can I directly inherit slave sites from this live, up and running master website?

Can I create a template based on 1 master site, and inherit slave sited based on the template, at the same time have the master site operational and reachable for my users?

Is this possible? I have read much here, and i have seen a video that explains master - template - slave scenario, the thing that confuses me is that the master sites seems like a website that is there, but at the same time it is not there, it is only a master-set in which all relevant components and templates are stored. However, one would have to fill in a domain name, therefore each master / slave is reachable from the web isn't it? I don't want that.

I simply want:

Master Site
-->Slave site derived from master site, log into master = log into slaves and vice versa
-->Second Slave site derived from master site, log into master = log into all slaves and vice versa
-->Third Slave site derived from master site, log into master = log into all slaves and vice versa

Logging into one of the slaves should log me into all slaves, including master. Userdatabasesd should sync, If a user registers on one of the sites (master or one of the slaves) the user should be available on all websited.

I use Community builder and JoomGallery that I preferrably want to share. Each slave has it's own template.

I am struggling a lot, cannot figure it out, sorry. You have put so much effort in trying to make us understand, but yet I simply dont know how to proceed.

I use Linux, have root access to everything, symbolic links are allowed, each slave should prefferably have it's own database (some shared tabled but I suppose that is what JMS takes care of). I also have a number of domain names registered, they all resolve to their corresponding virtual Joomla config at this moment since I have added websites via JMS.

What you describe is a "Single Sign-In" or shared login processing.

First of all, JMS does NOT perform andy synchronisation system.
It applies reall SHARING of data and therefore the user information are present only once.
So if you decide to share the users between the master and slave site, this is possible and the users will only exists in the master websites. The other websites will just have a kind of like using MySQL facilities to share MySQL tables.

In other words, if you decide to share the users, you will be able to use the same login between the website that you will have decided to share the user.

Second aspect is the "Single Sign In".
As exlained in the product detail, this only works with the same domain name.
So you can have different subdomain or subdirectories websites that are located on the same domain.
The "Single Sign-in" means that when a user is logged in a website, it does not need to relogin into another website that is on the same domain. The session remain open.
Otherwise he will have to relogin with the same login and password.

See product detail - content sharing and single sign-in
www.jms2win.com/download


See the list of extension that can be shared
www.jms2win.com/component/content/article/135
CB can be shared.

I understand that it is sharing at the MySQL level. That was clear already, and that is very nice indeed!

As for the single sign in, the slaves reside on the same domain physically (same hosting account). The domains are created with domain pointers in Direct Admin. This -I think- should work.

I want to thank you for all your effort in explaining all aspects of the software, thank you for the reply and the links!

I'll try and sort it out with that info.