- Install wordpress at sitename.com
- Setup multisite
- Create a new site at /wordpress1/
- Create a new site at /wordpress2/
- Install Buddypress plugin
- Activate buddypress on /wordpress2/ ( not network wide, just wordpress2 )
- Hey presto you have exactly what you want without the nightmarish usertable situation
Problems you will face with the login using a shared user table:
- The usertable isn’t the only shared table
- Roles and capabilities are intimately tied into the usertable, you now have 2 of these, where there should only be 1
- Upgrading everything will be a maintenance nightmare
- A lot of plugins will hate the setup you want
All of this is avoided by using multisite