Using Multi-db after installation

I’ve got a new multi-network which includes BP multi-networks. Each of the networks are mapped domains and work as expected. Site structure:
Main Site: http://beautyugly.com
Network: http://modelbu.com
Network: http://dancingbu.com
Network: http://cancerbu.org

When adding avatars to groups on one network, say activebu.com, it changes some of the avatars which are already in place on another network, say beautyugly.com. It was thought that multi-network isolates blogs, groups, and forums and so only user accounts are to be shared across the network.
So I'm wondering if using this plugin would help address this issue? If anything since I plan on offering blogs on the different networks while adding new networks could I benefit from this plugin, provided I'm able to use it without having to rebuild my network.

Any responses appreciated