Here is an example of the structure:

Main site: hosting user data, alpha UP, Alpha Registration, articles Other component and modules

slave site 1: hosting directory component not found on main site but sharing user data and alpha UP and alpha registration and articles

slave site 2: hosting a component found on main site but not found in compatibility list and running independent of main site and sharing alpha UP and alpha registration and articles and some menu items

slave site 3: hosting a component found on main site but not found in compatibility list and running independent of main site and independent of slave site 2 and sharing alpha UP and alpha registration and articles and some menu items

is this possible with using the same component but running independently of the other sites on the same database?

First, all the extension required for a slave site must be installed on the master event when they are not used by the master site.
The master website is the repository or the library where all the extension are present.

1) It is possible to create slave site that share the users.
Alpha User Point is also an extension that can be shared on Joomla 1.5.

Concerning the Alpha Registration, we don't know this extension and it is not defined in JMS Multisites. So you can not share it.
If you want that we review this extension to see if it can be defined in Jms Multi Sites and perhaps also for the sharing, please send us the extension in the attachement of an email. Our email is in the contact us.

By default each website has its own content for the extension except when you share the extensions. So you can have the same extension PHP code and have different data in the DB for this extension.
So you can have the same component with different data in each website.

The "Article Sharing for JMS" is an extension that allows reading articles comiing from other websites. So that you can share some articles between websites.
See demo video.
tutorial.jms2win.com/joomla/multisite-12...ingforjms/index.html

Yes it is possible to use the same component on the same DB. In this case, the websites have different table prefix.

ok I sent it in an email to your info account

it seems that the alpha recommend takes the user referral code and places it in recommend email maybe that one does not matter... but the alpha registration creates the code.. is that going to work across the sites. Will the new users get the same code across all sites?

It seems that the Alpha Registration extension does not use any specific table and only use core joomla table.
So if you share the user between website, this should work.