Two Dolphin Sites, Share Only Username Database - POSSIBLE?

I been looking and researching how to set up two dolphin sites that share ONLY the username database. Here is what i learned from reading all the forums related to this topic.

1st Method: Changing the inc/header.php

Result: every aspects of the database was shared; includes modules, username, header title, everything. So this was just a way to mirror a site.

2nd Method: (DON" KNOW WHERE TO START) I read from some forum that to achieve this I should have two database then just "BRIDGE" the two database for the username. So when a user signup on the main site, the information is also transfer to the subfolder site.

Is the 2nd method possible? If so, PLEASE help me to the right direction. Or is there a better way to Share only User Login information?

Extra Info:
Both Dolphins are version 7.0.5 on the same server
Location: www.mydomain.com and www.mydomain.com/subfolder

Thanks

The only way I know of to achieve this is to find the sign-up portion of the header file on your second network.

Then instead of using the path to it's database, link it to  /first network/ sign up database.

I hope it help a little.

~Gary

Thanks Gary for the insight. I have been looking but as you know Dolphin has very complex and confusing codes. I guess I am not an expert on this yet. Will keep looking.

I just came across this in mods - cross profile integration.  A bit expensive though $250 bucks.

http://www.boonex.com/unity/extensions/entry/Cross_Database_Profile_Synchronization

Wow...$250. Thanks for the info, did not know this was out there. For now it is a little too expensive for my pocket. But will keep this in mind.

Bump.

I have a major need for this. Anyone made progress outside the pricey module?

Dolphin support custom authentications modules. 

By default Facebook sign-in only is supported, but it should be other auth modules in the market.

So, actually event with default facebook login you will have single username sign-in on any number of Dolphin sites.

My problem is that I don't want to let Facebook maintain the management of the user profiles on their end. While the connect module makes it easy, I want to maintain my own member database with a master site, and allow those members to log into other sites within my same dolphin network (just different domain name and different module sets).

Unfortunately, there is no value in allowing a third party to maintain a members database for my site, or an open SSO if you will. Whoever holds the members holds the power!

Then setup own OpenID server and allow users to sign-in with only your OpenID account.

Have a look at modules with OpenID sign-in support:

http://www.boonex.com/market/search?q=openid&gse_filter=market