[wescleveland]

BuddyPress is amazing and I won’t be the least surprised if it can do what I need right out of the box. Alas, after searching through documentation and forums I have come up empty.
I would like to be able to have certain sub-domains be isolated from the rest of my site.
Suppose I have a primary domain (domain.com) with a number of sub-domains (sub1.domain.com, sub2.domain.com, sub3.domain.com, and sub4.domain.com). Is there a way I can set up BuddyPress so that sub1.domain.com and sub2.domain.com share the same BuddyPress instance as domain.com while sub3.domain.com and sub4.domain.com have isolated instances of BudyPress.
By “isolated instances”, I mean their groups, members, blogs, forums, etc. would not be visible by anyone outside of their sub-domain. In addition, group name, blog names, forum & topic names, etc. could be identical in each Isolated instance. E.g. sub3.domain.com and sub4.domain.com could BOTH create a group called “MyGroup”. Their group members would only see their version of “MyGroup”.
I noticed that the BPDB class has a set_prefix method and was wondering if maybe I could use this to create seperate instances of the BuddyPress tables for each isolated sub-domain. Perhaps calling $bpdb->set_prefix($sub_domain_prefix) during BP initialization with a prefix that is unique for that sub-domain. But, I really don’t know enough about BP yet to have a clue where that will land me.
Any thoughts would be GREATLY appreciated.

[@mercime]

Out of the box, BuddyPress has only one instance in a WP multisite installation and requires to be activated network-wide in order to aggregate information from subsites created.

This is not to say that it’s not possible to create BuddyPressMU (there are just awesome coders/programmers out there) — but with major changes coming up with BP 1.3, then WP 3.2, and then BP 1.4, etc how many times are you going to twist and turn to extend BuddyPress that way and get it working with all BP/WP plugins without the support and technical skills of a large community? But hey, that’s just me.

Of course if you’re one of the awesome coders/programmers I’m thinking of, this will not be an insurmountable challenge at all … it’ll be a walk in the park

Going back to your scenario, could create 4 physical subdomains (instead of one WP with 4 virtual subdomains) in addition to your main site and activate BP in each site = 5 BP instances. Others might like to chime in with better configuration.

[wescleveland]

Completely agree that the solution would have to be without hacking BP or WP in order to more easily support.future versions of both. Physical sub-domains is an interesting idea. It is one that I have considered and perhaps may land there. Your comments just reinforce that as a viable direction. Thanks for the input. It is appreciated.