I am using the Fabrik CCK Forms component to create new users in a slave site in my JMS. As you know, this JMS uses partial user sharing, which means that JMS is managing the users in a non-standard way.

Normally, in a standalone site (non-JMS) my Fabrik form is able to sync the new user registration to the #_users database table, using Fabrik's JUser form plugin to bind my mapped Fabrik user fields to the typical Joomla user profile fields, i.e., Name, Username, Password, Email, Usergroup, Block, Enabled, etc.

But in this case, it isn't binding the fields, since the form is trying to connect to the what I think are non-existent tables in the slave1 db and not to the separate partially-shared user tables.

I'm not sure how the users structure is managed by JMS. I see tables that look like slave1_users and slave2_users, and then I see a View table whose purpose I am not sure of but I'm guessing that it is what allows each slave's admin area to display the users when accessing Users/Manage in the admin?

If you have some ideas about how to accomplish this, I'd appreciate it.

When using the partial user sharing, in fact there are 2 tables that are used.
One that give the list of the users that are declared on the slave site
and another one that is the orginal #__users table filtered on the declared users.

So the name of the table #__users is still present but display a subset of the full list.
I don't know how fabrik is working internally but the #__users still exists.
The potential issue is that when adding with Fabrik, it may not be saw as it is not also declared in the other table to mention that the user is granted to this site.

So you have to analyse if fabrik store effectivelly the #__users but are not be displayed because not also declared into the other table.