Hoping to benefit from the experience of others. This question is really multiple potential questions so I'm hoping someone can steer me to the best solution to keep me from all the trial and error.


So I have set up a WordPress v3.0.3 site currently with about 20 users and about 25 pages of content and I realize I needed a discussion forum for which I think the P2 Theme will work really well. I installed another copy of WordPress in the /discuss/ subdirectory and then went about trying to share the user tables by setting CUSTOM_USER_TABLE and CUSTOM_USER_META_TABLE only to find that setting those constants are not sufficient because of issues with the COOKIE_DOMAIN and COOKIE_PATH, issues with capabilities that would require hacking core to fix, and it seems lack of support from the core team for multiple sites with the same user tables. So I fear heading down a rabbit hole of lost time trying to make this work.

So I thought maybe Multisite would be the solution which is unfortunately something that I've had very little experience with yet. However it seems that I can't just convert to multisite (according to @EAMann) but instead need to create a new install and then rebuild from there. Not knowing what that will break (i.e. will my users roles and capabilities transfer? Will the members plugin I'm using work? Are there any other concerns?) I'm also afraid to take that path unless I know it'll work well.


So in summary, what's the best way to get a site set up to have a main site and to use the P2 Theme for discussions in a subdirectory of the main site, to be able to use one user database and ideally to have a single login? (though single login is the least important consideration at the moment.)

Thanks in advance for the help.

  • P2 is far from a discussion forum. But if you really think it's what you want, why not just create a custom theme, using P2 as a base? Dec 19, 2010 at 23:02
  • @AmbitiousAmoeba - Thanks. Acknowledged that P2 isn't really a forum but it is what I need for this use-case. I did create a child theme for P2, but that wasn't the crux of the question. The question was how to get shared user bases working and @andrea_r handled that for me. Thanks! Dec 20, 2010 at 2:38

1 Answer 1


"However it seems that I can't just convert to multisite"

I have no idea why he told you that, because it is possible. I mean,.... it's kind of the whole point of why multisite was merged in - so existing sites could just turn it on.

User roles on the main site will stay exactly the same. there may be a couple plugins that don;t like the network, but... if they are used on your main blog, you're probably fine. If one is broken, there's likely a replacement.

I mean, multisite is pretty common now, most of the plugin issues are worked out. A good way to check, if it's the membership plugin you're worried about is to go to their site and/or support forums and ask them. ;)

The only "catch" right now is this:

You want a subfolder install. In that setup, the main blog will get a /blog/ stuffed in the permalinks to prevent conflicts with site urls and page urls. this can mess up your permalinks (obviously).

But you can ALSO disable it after installation. Go to Super Admin -> Sites and click edit on the main site. Remove it in any of the fields. Presto, problem solved and you now have multisite on your existing blog.

So to answer your last question - just enable multisite. If you're really nervous, make a backup of your site, install it locally, and do it there as a test run.

  • Thanks! Turns out you answered after I did a new install, but what they hey, your answer will help someone else maybe. BTW, I must have confused you; I didn't want a subfolder install except for the P2. So I wanted http://example.com/ and http://example.com/discuss/ and it worked out fine. BTW, the Members plugin works but doesn't have sync capability across sites which would be nice. Dec 20, 2010 at 2:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.