What I mean is the following. I have a wiki mapped to my custom domain (www.mydomain.org) and three others mapped to subdomains (wiki1.mydomain.org, wiki2.mydomain.org, etc.), all of which are thematically-related. The way they're now, all these wikis are independent from each other, in such a way that membership in one of them does not imply membership in the others.
If possible, I would like to integrate them, so that becoming a member of the main wiki (www.mydomain.org) would automatically allow access to the subdomain wikis as well. Also, that would allow the content to be unified, so that clicking on a given tag would list all the relevant pages in all my wikis. Is that at all possible? If not, could it be implemented in the (near) future?