Thread:Project:Support desk/Wikifamily and Shared database setup/reply

What you explain should work without problems. For the user being automatically logged in on all wikis when he logs in in one of them, all wikis should have the same parent domain, because of $wgCookieDomain (for example, if your wikis are en.mainwiki.com, de.mainwiki.com, etc). Otherwise, they should log in on each wiki separately, although having a shared user table will make them have the same user account with same password, etc.