interesting? you can use sunrise.php to support multiple domains with one user table, but I’m not sure how site_url() (BuddyPress) would react to it. Search for wpmuguru. He’s really good with configuring multiple domains/databases on multi-user. It would be interesting to test and with enough custom code, you could make almost anything happen
ps.. you should mark the topic as resolved since this really isn’t a direct support question.
I am also wondering how I can run WPMU + buddyPress across 5 different domains with just 1 user-table ?
I guess I would need 5 separate installs and 1 common user-table ?
Is this possible ?
Now that BP can be installed on user blogs can’t you use that + I coulda swore there was a plugin before that allowed people to use a different domain for their user blog. Or maybe I’m dreaming it all.
There is a config file setting that will allow you to run BP on all of your user blogs… so you could run BuddyPress on as many sub-domains as you wish. I have no idea how you might run one instance on multiple fully qualified domains however. That doesn’t sound possible to me. But I’m no networking guy.
define ( 'BP_ENABLE_MULTIBLOG', true );
https://codex.buddypress.org/how-to-guides/changing-internal-configuration-settings/
Actually…. yeah, you can do this in MU. Theoretically. Buddypress doesn’t care what the domains are, and it’s not multi-site aware. (the old site term, not the new one)
So I’m pretty sure you can do this with the multisite plugin, bp & mu, without too much tinkering.
disclaimer: not wpmuguru, but I work in the same office 
Hi Andrea,
many thanks for your comment.
it seems the “Multi-Site-Plugin” works with subdomains only ?
Is there a chance to get this working with real domains, say if I do have 5 different domains and want to run 5 WPMU-installations with ONE user-table ?
hmm… just wondering whether the Multi-Site-Plugin will work with WP 3.0 when merged with WPMU ?
Multi-Site plugin
– Does not support remote login. Mapped domains must be logged into separately.
Does this mean it is not possible to run 5 WPMU+BP installs and have ONE single login across all 5 domains ?
I;d prefer to answer these question by email to not clutter up the forums, cuz it’s a paid thing. 
(mods, feel free to make your call)
But in short:
– it works in either kind of install
– it also works with multiple TLDs. I use it to run atypicalife.net and my family’s blogs on the same exact WPMU installation that runs wpmututorials.
– it works fine with 3.0, we’ve been using it on trunk, but it meeds renaming.
– remote login means saving the cookies from one domain to the next. your one user login & pass works for all if you’re assigned to those blogs.
i have wpmu + bp + bpress on multiple domains with a single sign-on, however when using bp-default, the theme is always displaying the main url rather than the blogs url (mapped with donncha’s domain mapping plugin). shouldn’t site_url in header.php display the blog rather than the host? if not, what whould be the correct function to call it?
No, the bp defaul theme uses a function to call the main BP site. You need to replace it with the standard wp function to get blog_url.
makes absolute sense – thanks a lot!
Been a while since I’ve been back here; nice to see so much progress has been made!
Going through an overhaul and update of our BP setup and I’m curious if this was ever built into the codebase. Can Buddypress be applied, easily, across domains?
I was looking for exactly the same thing and I came across this (http://premium.wpmudev.org/project/multi-domains/), I downloaded it already and I’ll start working on it today and I’ll get back and let you all know how it turned out
WOW!!! it worked perfectly I really didnt expect it to go so smoothly, I also have to give credit to my hosting company (host gator) for being so easy to work with
